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Chapter 2

DETAILS OF APPARATUS

AND CHARACTERIZATION TECHNIQUES

2.1. Introduction

Naphthalocyanines are novel Phthalocyanine type materials widely used in

the area of thin film active devices for optoelectronic applications. Though the study

of thin film phenomena coupled with organic semiconductors dates back well over a

century, significant applications regarding those lasted only for two decades. Today

thin film science is projected to be one of the major processing techniques to

fabricate electronic, optical and magnetic data storage devices, fuel cells and solar

cells. Latest developments in thin film technology reside in the nano solar cell

fabrications and thin film batteries for nano markets. The growing needs for different

types of thin films ensure suitable deposition techniques, potential materials and apt

coating substrates. Modern electronics choose organic semiconductors as active

layers from their inorganic counter parts due to the favourable electrical properties.

Physical Vapour Deposition (PVD) is one of the best methods for sublimation at low

temperature without undergoing decomposition for organic semiconductors,

especially phthalo and naphthalocyanines. In this research work, efforts have been

taken to fabricate (metal free, Zinc and Vanadyl) Tert-Butyl substituted 2,3

naphthalocyanines thin films using PVD technique onto glass substrate. By varying

different factors like thin film thickness, post deposition air and vacuum annealing

and by heating substrate; the basic electrical, optical, structural and surface

morphological properties are studied. As a part of application level study, we

irradiate respective thin films with different dosage of gamma rays and study the

defect level conduction mechanism to show their use in the field of dosimeteric

sensors and sources. This chapter briefly describes the PVD technique employed for

TTBNc thin film fabrication and the theory behind different characterization

techniques like D.C. electrical conductivity, UV-Visible spectroscopy, X-ray

40

diffractogram (XRD), Scanning Electron Microscopy (SEM) and Atomic Force

Microscopy (AFM).

2.2. Thin film deposition techniques

Organic thin films with high structural order are required to implement the

novel electronic and optical application that have been proposed for devices based

on small conjugated molecules. Among the candidates for technologies such as large

area and mechanically flexible organic electronics, naphthalocyanines stand out for

relatively high field effect mobility and their ability to form ordered thin films on

various types of substrates. Much of the physical phenomena associated with bulky

naphthalocyanines are well known. However, this cannot be said about

Naphthalocyanine thin films. Thin film active materials, defined by dimensions on

the order of microns, give relatively new research output apart from their bulky

counter parts; still they have some scientific infancy [1, 2]. Structures could be

designed to interact and be built at the micron level using different thin film

fabrication technology which comes under three major headings:

1. physical methods

2. chemical methods and

3. sputtering

Each of the above mentioned methods can be used to prepare thin films

from a variety of materials like metals, semiconductors, insulators or dielectrics

and each of them has its own advantages and disadvantages [3]. From here,

onwards we restrict our discussion only thermal evaporation method which we have

employed to prepare thin films for the present study.

2.3. Thermal evaporation

Among the most widely acceptable techniques for thin film deposition,

thermal evaporation method is a versatile and flexible one for producing deposits

of organic semiconductors. Basically it involves three steps, boiling or subliming

of source to form its vapour, transport of the vapour from the source to the

substrate and condensation of the vapour on the substrate. The basic physics of the

41

process contains elements of thermodynamics, kinetic theory of gases and

condensation phenomena [4].

Solid materials are sublimed under high vacuum when heated to

sufficiently high temperature [5]. The condensation of the vapour on to a cooler

substrate yields thin solid films. This method has the following advantages.

1. Impurity concentration in the film is minimum.

2. Material boils at lower temperature under vacuum.

3. Growth can be effectively controlled.

4. Mean free path of the vapour atom is considerably larger at low pressure

and hence a sharp pattern of the film is obtained.

5. Wide variety of substrates.

The evaporation rate and hence the condensation have wide limits, depending

upon the purity of source material used. Characteristics of the prepared films are

determined by parameters such as temperature, type of substrate, deposition rate and

residual atmosphere. All these parameters can be controlled in the thermal evaporation

method. More than that, single evaporation can give films of different thicknesses. We

have used here molybdenum boats and tungsten baskets for evaporation of materials.

Film of high purity can readily be produced with a minimum of interfering conditions.

The nature and properties of evaporated thin films depend on factors as shown below.

1. Nature and Pressure of residual gases.

2. Vapour beam intensity.

3. Nature and conditions of substrate.

4. Temperature of vapour source and velocity of impinging molecule.

5. Material contamination from vapour source.

2.4. Vacuum coating unit

The type of vacuum equipment needed obviously depends on the desired

purity of the film. Detailed reviews on various types of vacuum systems and their

42

ultimate pressures are given by Holland [2], Carewell [6] Dushaman [7] and Roth [8].

The vacuum system employed to deposit and characterize thin film in the present

work contains an assortment of pumps, tubes, valves and gauges to establish and

measure the required reduced pressure as shown in Figure 2.1. Basically the

vacuum system “Hind Hivac” vacuum coating unit model No. 12A4D consists of

0.4m diffusion pump backed up by oil sealed rotary pump. Ultimate pressure

obtained in a 0.3m diameter steel bell jar is of the order of 8×10-6mbar. It has

setups of electron beam evaporation and flash evaporation. Most of the evaporation

is carried out at a pressure of (1-2)×10-5Torr. The pressure measurement in the

system is done by means of Pirani and Penning Gauges (6 and 7 in Figure 2.1)

provided with the system. The Pirani gauge model Hind Hivac-A 6 STM is used to

measure vacuum in the range 0.5×10-3Torr. The Penning gauge model STM 4 is

used to measure vacuum in the range 10-2 to 10-6Torr in two ranges with instant

range – charger provided by a toggle switch.

Figure 2.1 Schematic diagram of a vacuum coating unit with

1. bell jar 2. diffusion pump

3. rotary pump 4. control panel

5. L. T control 6. pirani gauge

7. penning gauge

43

The system is accompanied by a digital thickness monitor model number

DTM-101 having a temperature controller cum monitor to show the interior dom

temperature (30oC) at the time of coating and a display setting to show the rate of

coating. A schematic diagram showing vacuum chamber with thickness monitor is

given in Figure 2.2.

Figure 2.2 Schematic diagram of vacuum chamber and DTM: Substrate -1,

Shutter-2, Quartz crystal-3, Molybdenum boat-4, Oscillator -5, DTM- 6.

2.5. Purity of materials

If the evaporant is contaminated, the deposited thin film gets

contaminated. Usually high purity materials are used in this work. The source

materials used in the present study are originally procured from Aldrich Co.Inc.

WI., USA. The purity of materials is further checked with CHNS (Carbon-

Hydrogen-Nitrogen-Sulphur) analysis. The contents along with the rated purity

are given in the Table 2.1.

44

Table 2.1 Percentage of Carbon, Hydrogen, Nitrogen and Sulphur in the source materials along with the rated purity

Material C% H% N% S% Total% Rated%

TTBNc 69.73 13.19 14.07 0.002 96.99 97

ZnTTBNc 71.69 01.94 10.28 0.004 83.91 84

VTTBNc 69.49 04.57 09.87 0.007 83.94 84

The rated purity for metal free matches while metal bearing TTBNc shows

a deviation from Sigma product informations; those are 97%, 90% and 95%

respectively for TTBNc, ZnTTBNc and VTTBNc compounds. Here it may be

taken that remaining 6% going to Zinc percentage purity for ZnTTBNc and nearly

10-11% contributed for V=O (Vanadium double bonded with Oxygen) molecule in

VTTBNc.

2.6. Substrate cleaning A wide variety of cleaning procedures are available to develop good quality

thin films. Highly polished and thoroughly cleaned glass substrates are used here

for deposition of films. First, the substrates are cleaned using liquid detergent.

Then it is kept in dilute nitric acid for some time. After this, the substrates are

cleaned using distilled water. Then the substrates are agitated in acetone. Finally

the substrates are dried in hot air.

2.7. Thin film preparation Thin films are evaporated on to clean glass substrates using thermal

evaporation method. Thermal evaporation is a simple method in which the material

is created in a vapour form by means of resistive heating. On heating a material in

vacuum, sublimation takes place and the atoms are transported and get deposited

on to pre cleaned substrates held at suitable distance at desired temperatures. The

material for deposition is supported on a source which is heated to produce desired

vapour pressure. The requirements for the source are that it should have a low vapour

pressure at the deposition temperature and should not react with the evaporant. The

shape of the source is designed and fabricated in such a way to hold the evaporant

45

material [9]. The semiconductor is evaporated using Molybdenum boat and Tungsten

baskets as the source for coating electrodes. The unit is operated at 10V/100A ratings

of the step down transformer.

2.8. Thickness measurements

Average thickness measurement for all the thin films coated at a time is

made by digital thickness monitor along with the coating unit. For accuracy,

different methods are employed in deposited thin film for thickness measurements

[10]. In our laboratory, optical techniques are used for reconfirmation of thickness

measurement. This technique is used for both opaque and transparent thin films.

The basic principle behind this technique is the interference of two or more beams

of light reflected or transmitted from the bottom and top of the film the thickness

of which is to be measured. The condition for maxima in reflection will be the

condition for minima in transmission and vice versa.

For opaque films, sharp step-down to substrate plane must be first

generated either by a deposition through a mask or by subsequent etching. For

practical purposes the fringes formed are classified as the two cases of multiple

beam interferometry. They are Fizeau fringes of equal thickness and FECO fringes.

We have used Tolansky’s multiple beam interference method for the determination

of the thickness of thin film.

2.8.1. Tolansky’s multiple beam Fizeau fringe method

Figure 2.3 shows the schematic representation of Fizeau fringes produced

by multiple beam interference. The technique can be employed when the film to be

studied remains stable in vacuum and can be coated with highly reflective layer

[11]. The film is deposited on the glass substrate. A sharp shadowing with sharp

masks during deposition produces edge on the film. The film is then coated with a

highly reflecting silver layer. A second glass plate with a silver coated surface and

having some percentage of transmission is lowered on to the glass substrate and the

whole system is illuminated with a parallel beam of monochromatic light of

wavelength (λ=5893Ao) from a sodium vapour lamp.

46

Figure 2.3 Schematic representation of the multiple beam interference method a) Fringe pattern b) Arrangement and c) Sample with step

At a small distance between two glass plates, when the cover glass is tilted

slightly, multiple beam interference fringes are shifted by a distance ‘x’. In the

region of sharp edge, the fringes are shifted by a distance ‘∆x’ [12]. A shift ‘∆x’ in

‘x’ correspond to a thickness step of λ/2 and the thickness of the film is given by,

T =

∆x

x

2

λ (2.8.1.1)

One of the varying parameters for thin films is its thickness and it gets

varied by placing the glass substrate on different positions inside the evacuated

chamber or by coating the thin films for different thickness by fixing all other

varying parameters like internal pressure, substrate temperature, primary and

secondary current and density. Thickness variation may result in the variation of

electrical, optical, structural and surface morphological output of semiconducting

thin films.

2.9. Sample annealing The samples are annealed in a specially designed furnace to change their

properties. It consists of a coil of Kanthal (AI grade temperature range 1150 -

13500C). Figure 2.4 shows the experimental set up for sample annealing. To avoid

heat loss, it is surrounded by a thick package of fire brick silica whose working

temperature is 11000C and the melting point is 17100C. The width of the heating

47

element is about 20cm. The filament is also covered with sillmate (Al2O3 - SiO2)

tube, maximum working temperature is 15000C and melting point is 17100C.

Figure 2.4 Photograph of the furnace and temperature controller

It helps to provide uniform heating region at the centre of the tube. In

addition, it avoids any thermal shock during the annealing process. The

temperature of the heater is controlled and recorded by a digital temperature

controller cum recorder. Apart from air annealing, vacuum annealing is also done

on thin films by placing them inside an evacuated chamber in complete darkness

due to photosensitivity of Naphthalocyanines. A rough vacuum of 10-3mbar is

created inside the chamber using an external rotary pump. Temperature variation is

done on thin films under vacuum using a Chromel-Alumel thermocouple placed in

close proximity of the samples.

2.10. Substrate heating Substrate heating can be done within the set up of the coating unit by

connecting Substrate Heating (SH) controller to the substrate holder in evacuated

chamber. The internal settings like placing of copper constantan thermocouple over

the substrate to control the suitable substrate temperature. The voltage variation in

SH controller, is needed to create suitable temperature. For example, inorder to

create 100οC in the substrate holder, we have to suitably adjust the SH controller

voltage to 40V A.C. with which it shows a maximum variation of ±5οC. At that

time there is a change in the primary current to 2.5µA and secondary current to

55µA without changing the base pressure (1×10-5mbar).

48

2.11. Gamma ray irradiation Gamma chamber- 5000, a compact self shielded 60Co irradiator is used in

the present study to irradiate gamma rays to thin film samples to study high energy

ray impact on thin films. Gamma chamber is highly applicable in phthalo-

naphthalocyanine research applications that require irradiation materials with

ionizing radiations of varying doses. By fixing the density of materials to unity,

present dose rate is fixed in gamma chamber. For the apparatus, the dose rate

decreases 1.1% Gray/month. Due to the decrease of dose rate, the same apparatus

requires different time periods for creating a suitable irradiation dosage at different

time periods. Presently, we find the dose rate to be 1284.99Gray/hour. So, for the

irradiation of 500Gray gamma ray on thin film samples we require 23minutes

20seconds, for 1000Gray irradiation it needs 46minutes 41seconds and 1500 Gray

irradiation takes 1hour, 10minutes and 2seconds.

2.12. Characterization techniques Micro and nano structures, crystallinity, impurity content, chemical

composition, surface morphology, application of light and electromagnetic field

etc. influence various properties of thin films. The characterization of thin film

micro structure is necessary for improving of the performance quality of various

devices. The above mentioned favourable factors strongly depend on thin film

thickness, substrate heating, post deposition air and vacuum annealing, high energy

electromagnetic beam irradiation, choice of substrates and conditions of thin film

preparations. Some of the important film properties and characterization

techniques are as follows.

2.12.1 Conductivity measurements

The electrical conductivity measurements are carried out in a conductivity

cell. The cell consists of a thick walled cylindrical chamber with a bottom flange

and four side tubes made of stainless steel. Three side tubes are closed air tight

with glass windows and are used in spectroscopic studies. The remaining side tube

is connected to a rotary vacuum pump and the chamber can be evacuated to low

pressure of 10-3mbar. The inner tube is made of stainless steel pipe which has been

welded to a large copper finger. The liquid nitrogen cavity and the heater coil help

49

the sample to attain the required temperature very quickly. The outer enclosure is

made leak proof by using an ‘O’ ring which rests inside the groove on the flanges.

A sample holder fixed at the copper finger can hold the film with the help of

screws. The outer surface of the copper finger is covered with mica sheets and the

heating coil is wound over it. The electrical leads are taken out through Teflon

insulation. A D.C. power supply is used to heat the heater coil. The electrical

leakage current through the mount is by-passed to earth by grounding the inner

tube. The leads of the electrodes are taken out using Bi Noded Circuit (BNC)

connector. A Chromel-Alumel thermocouple in contact with the sample senses the

temperature. Temperature of the sample in the cell can be varied from liquid

nitrogen temperature to 400 0C.

Electrical conductivity measurements are carried out using Keithley

programmable electrometer model No.617. It is a highly sensitive instrument

designed to measure voltage, current, charge and resistance. The very high input

resistance, low input offset current and sensitivity allows accurate measurements.

The measuring range is in between 10µV and 200V for voltage measurements,

0.1pA and 20mA in the current mode and 10fC and 20nC in coulomb mode. The

resistance can be measured in two modes; (i) constant current mode and (ii)

constant voltage mode. Due to the high input resistance, a resistance as high as

200GΩ can be measured in the constant current mode. Using constant voltage

mode, resistance as high as 1016Ω can be measured. In this mode the measured

resistance is automatically calculated from the applied voltage. The model 617 has

a built in voltage source which can be used to apply a current I, through the

unknown resistance R. The insulation resistance is then automatically calculated by

the instrument as R =V/ I, where I is the current through the resistance and V is the

programmed voltage. The voltage can be programmed between -102.35V and +

102.4V in steps of 50mV and the maximum measurable output current is 2mA.

The instrument is capable of an internal 100 point data store and that can be used

to login a series of readings. The fill rate of data store can be set to specific

intervals according to the experimental conditions. The photograph of

experimental set up used to measure the electrical properties and analyse the

50

device characteristics is given in Figure 2.5. The four probe technique was not

satisfactory for apparently high resistivity films because the order of magnitude of

the film [13].

Figure 2.5 Photograph of electrical conductivity experimental set up

The longitudinal structure of thin film with silver coated on two sides as in

Figure 2.6 is used as source for measuring the conductivity by two probe analysis.

Figure 2.6 Longitudinal structure of thin film

2.12.2 U.V- Visible Spectrophotometer

CARY 5000 (Version No. 1.09) has been used to record the optical

absorbance of the films in the UV-Visible and in NIR region. It is a double beam

system employing a static beam splitting half mirror which sends the light beam

from the monochromator through the sample and the reference substrate equally.

Semiconductor film

1cm 1cm 1cm 0.5m 0.5m

1cm

4cm

Thick Ag film Glass substrate

Glass substrate

51

The light sources are either Deuterium lamp or Halogen lamp. The Deuterium

lamp produces wavelength starting from 200nm. The halogen lamp produces

wavelength up to 3100nm. Switching wavelength of light source can be set to any

value with in the range of 295 to 364nm. The lamps can be automatically

interchanged according to the wavelength needed. All the optical elements except

the light source are isolated from the external atmosphere by the window plate so

as to make the set up dust free. The slit width of the monochromator is fixed at

2nm. The collimated beam is allowed to split by the half mirror into the sample

and the reference beam. Two voltages are produced by the detector which is

proportional to the light intensities of the reference and sample beams respectively.

These two voltages are amplified and fed to the electrical system. The photograph

of CARY 5000 (Version No. 1.09) double beam mode spectrophotometer is as

shown in Figure 2.7.

Figure 2.7 Photograph of CARY 5000 double beam mode spectrophotometer

The optical behaviour of a material is generally used to determine its

optical constants, refractive index (n) and extinction coefficient (k). Films are ideal

specimens for reflectance, transmittance and interferometric measurement. The

methods are generally classified into (1) Reflection method, (2) Reflection and

Transmission method and (3) Interferometric method. Out of these three methods,

Reflectance method is used to determine the optical constants of the films in this

work.

52

2.12.3 X-ray Diffractometer

The diffraction of X-rays by micro crystals in powder and film results from

a scattering process mainly due to electrons of corresponding atoms without

change in wavelength (λ). The intensities of diffracted beams are determined by

the positions of the atoms within the unit cell. So, by measuring the intensities of

the diffracted beams, idea about the atomic positions can be obtained. The velocity

of propagation of X-rays in vacuum is found to be same as that of electromagnetic

radiations and they exhibit dual nature. In the phenomena of refraction,

interference, diffraction and polarization, X- radiation acts as waves, giving

thereby to λ a real significance. But in the phenomena of photoelectric effect,

Compton effect, the appearance of sharp spectral lines and a definite short

wavelength limit of continuous spectrum, the energy of X-radiation appears to

propagate in quanta defined by the values of hν. When a monochromatic beam of

X-radiations having a wavelength (λ) falls upon the atoms in the Bragg plane, a

wavelet of scattered radiations spreads out from each atom in all directions.

Siemens-EQBCL015 X-ray Diffractometer (Model No. D5005) is used for the X-

ray diffraction of both powder and thin film samples and the schematic diagram for

Siemens-D5005 model is given in Figure 2.8.

Figure 2.8 Schematic diagram for Siemens- D 5005 model X-ray Diffractometer

Since X-rays are much more penetrating than ordinary light, it is essential

to consider the reflection at several such layers. At each layer there is a partial

reflection and the X-ray beam will be completely absorbed after penetrating a large

53

number of layers. Now these reflected wavelets will reinforce themselves only

when they meet in the same face, the condition for which is that the path difference

between two such rays must be an integral multiple of wavelength. Thus the

condition for diffraction is

θλ sin2dn = (2.12.3.1)

Where d is the distance between adjacent planes in the crystal and θ is the

glancing angle, n is the order of reflection and λ is the wavelength of the incident

X-radiation. This characterization is used as a very important tool for the

identification of phases and crystallographic plane of grain growth. From the XRD

data, we attempt to calculate the mean crystalline size, dislocation density and

structural strain from the θ value and full width at half maximum (FWHM) of the

diffraction peak [14].

2.12.4. Scanning electron microscope

Scanning electron microscopy (SEM) is one of the most versatile and

useful instruments which provide morphologic and topographic information about

the surfaces of solids that is usually necessary in understanding the behaviour of

surfaces. It provides better depth of focusing and details than by the conventional

techniques. The surface with a rough topography can be examined. It is possible to

have a three dimensional view of the surface. In addition, in-situ observation of

surface morphology changes during oxidation of the specimen is also possible.

In a scanning electron microscope, the surface of a solid sample is scanned

in a raster pattern with a beam of energetic electrons. The back scattered and

secondary electrons produced from the surface in this process serve as the basis of

scanning electron microscopy. The secondaries are formed by the interaction of the

primary electron beam with the loosely bound electron of the surface atoms and

their emission is very much sensitive to the incident beam direction and the

topography of the surface atoms. The contrast depends on the rate of secondary

electron yields and the incident angle of the primary beam to the surface element.

When the electron beam scans the specimen surface, there will be a change in the

secondary electron emission according to the surface texture. In the present study,

54

SEM is taken using the instrument JEOL/EO (Model No. JSM- 6390) and the

schematic diagram is shown in Figure 2.9.

Figure 2.9 Block diagram of JEOL-JSM- 6390 SEM instrument

From the SEM image, the surface morphology of thin film sample and the

average grain size for nano particle identification is well interpreted [15, 16, 17].

2.12.5 Atomic force microscope

Thin film surfaces can be topographically imaged to an atomic level

resolution by making use of a microscopic technique like Atomic force microscopy

(AFM). The principle of AFM is simple: a tip of nanometer scale sharpness is

mechanically contacted with the surface to probe the morphology. High instrument

resolution is obtained using a very sharp Silicon Nitride probe. The sample is

mounted under the probe and it is moved in X, Y and Z directions by a ceramic

piezo-scanner. The tip is mounted on the edge of an elastic cantilever (100-200µm)

of low spring constant to keep the probe in contact with surface. Deflection of the

tip along Z axis, due to different height on the surface of the sample, is monitored

by an optical laser. With all this information, it is possible to obtain a 3D scan of

the surface. Property-sensitive imaging modes can also be performed simultaneous

to topographic imaging. Tip chemistry can be modified for controlled studies of

probe-sample interaction. Many of the essential experimental features of AFM

parallel to those of Scanning Tunnelling Microscope (STM).

55

There are three basic modes of operation associated with AFM such as Non

contact AFM (NC-AFM), Contact AFM and tapping mode. In the non- contact

AFM mode, the cantilever is located tens to hundreds of angstroms from the

specimen surface. To prevent the surface contact, a stiff cantilever is used resulting

in low tip- specimen forces of ~ 10-12N. NC-AFM has the ability to probe soft or

elastic materials and minimization of both surface contamination and tip

degradation. Normally, the spatial resolution of AFM is poor than that of STM.

But with sharp probe tips, a stiff cantilever, and operation in ultra vacuum, atomic

resolutions have been readily imaged by it.

In contact AFM mode, also known as the repulsive mode, the tip actually

makes physical contact with the surface, and force in the range of 10-6 to 10-8N is

typically generated. The block diagram for a general contact mode AFM is shown

in Figure 2.10. It grasps clear topological evidence apart from the former type.

Tapping mode is having both the advantage of NC-AFM and Contact type. It

sweeps through the surface touching at regular intervals.

Figure 2.10 Block diagram for contact mode atomic force microscopy

Here we employ Veeco 3-D nanoscope in contact mode to take the topological

image of thin films and the photograph is as shown in Figure 2.11.

56

Figure 2.11 Photograph of Veeco 3-D Nanoscope with contact mode AFM

The Nanoscope III-D AFM is primarily used to study the topography of

semiconductor surfaces and other materials. It can operate in contact mode (where the

tip is in continuous physical contact with the probed surface) or in tapping mode.

Tapping Mode AFM, the most commonly used of all AFM modes, is a patented

technique (Veeco Instruments) that maps topography by lightly tapping the surface with

an oscillating probe tip. The cantilever oscillation amplitude changes with sample

surface topography, and the topography image is obtained by monitoring these changes

and closing the Z feedback loop to minimize them. This eliminates shear forces which

can occur in contact mode and so minimizes the damage to soft samples. The Multi

Mode system features multiple scanners that permit the user to tailor the system for

individual research. Scanners with large scan ranges up to 120µm in the X-Y plane, and

a Z range up to 5µm, as well as high-resolution scanners with 0.4mm X-Y plane and

submicron Z range are available [18, 19]. The instrument can also perform scanning

capacitance measurements. The Nanoscope IIIa controller provides 16-bit resolution on

all three axes, with three independent 16-bit Digital-to-Analogue Converters (DACs) in

X and Y for control of the scan pattern, scaling, and offset [20]. The III-D Nanoscope

image analysis and presentation software contains powerful algorithms for the

measurement and presentation of the research results including: cross sectional analysis,

roughness measurement, grain size analysis, depth analysis, power spectral density,

histogram analysis, bearing measurement and fractal analysis [21].

57

References

1. F. H. Moser and A. L. Thomas, Phthalocyanine Compounds, Reinhold Pub.

Co. (1963).

2. L.Holland, Vacuum Deposition of Thin Film, John Wiley, New York (1956).

3. K. L. Chopra and S. R. Das, Thin Film Solar Cells, Plenum Press,

NewYork (1983).

4. J.E. Mahan, Physical Vapour Deposition of Thin Films, John Wiley &Sons,

New York (2000).

5. L. Eckertovà, Physics of Thin Films, Plenum Press, New York (1986).

6. H. C. Carewell, Physics of Thin Film - Vol. 1 Ed., G. Hass Academic Press,

New York (1963).

7. S. Dushman, Scientific Foundation of Vacuum Techniques - 2nd edition, John

Wiley and son, New York (1962).

8. A. Roth., Vacuum Technology, North Holland Amsterdam (1976).

9. K. L. Chopra, Thin Film Phenomena, McGraw-Hill, New York (1969).

10. L. I. Maissel and R. Glang, Handbook of Thin Film Technology, McGraw-

Hill, New York (1970).

11. W. R. Runyan, Semiconductor Measurements and Instrumentation,

McGraw-Hill, New York (1975).

12. M. Ohring, The Material Science of Thin Films, Academic Press INC., Harcourt

Brace Jovanovich Publishers, Boston (1992).

13. S. A. Tomas, O. Vigil, J. J. Alvarado-Gil, L. Lozada-Morales, and

O.Zelaya-Angel, J. Appl. Phys. 78(4), 2204 (1995).

14. M. M. EL-Nahass, A. M. Farid, A. A. Attia and H. M. Ali, Fizika A

(Zagreb) 15, 147 (2006).

15. K. Kawauchi, K. Ogura, C. Nielsen, A. Brooker and R. Bennett, Microsc.

Microanal. 10, 958 (2004).

58

16. E. D. Boyes, Microsc. Microanal. 13, 584 (2007).

17. A. J. Lockley and R. E. Mayville, Microsc. Microanal. 8, 1308 (2002).

18. Park Scientific Instruments, A practical guide to scanning probe

microscopy (1997).

19. N. Yao and Z. L. Wang, Handbook of Microscopy for Nanotechnology

(2005).

20. Veeco Scanning Probe Microscopy Training Notebook, Version 3.0 (2000).

21. G. Binning, C. F. Quate and C. Gerber, Phys. Rev.Lett. 56, 930 (1986).