Design, Growth & Fabrication of In x Ga 1-x N (0 ≤ x ≤ 0.25) Based Solar Cell Dissertation by Rajkumar Sahu Advisor: Mr. Sonachand Adhikari Co-advisor: Dr. Sanjay Tiwari CSIR-Central Electronics Engineering Research Institute, Pilani , Rajasthan School of Studies in Electronics & Photonics , Pt. Ravishankar Shukla University, Raipur May 22, 2014 Rajkumar Sahu [email protected]
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Design, Growth & Fabrication of InxGa1-xN (0 ≤ x ≤ 0.25) Based Solar Cell
Dissertation by
Rajkumar Sahu
Advisor: Mr. Sonachand AdhikariCo-advisor: Dr. Sanjay Tiwari
CSIR-Central Electronics Engineering Research Institute, Pilani , RajasthanSchool of Studies in Electronics & Photonics , Pt. Ravishankar Shukla University, Raipur
Operation of a solar cell• Working principle of Solar Cell based on Photovoltaic effect.• Photovoltaic effect is generation of Electric power from light.• Single junction solar cell is simply PN junction under illumination of light.
• Operating diode in fourth quadrant generates power.
Efficiency - 25%Loss mechanisms in a single junction solar cell.
Transmission of low energy photons ~23%.Thermalization of high energy photons ~29%.Junction/Contacts ~14%.Recombination due to material quality ~5%.Other: Curve factor Loss, Shading, Reflection ~5%.
Solar cells with decreasing band gaps are stacked with greatest band gap on the top.High energy photons are absorbed by top layers decreasing thermalization losses.Low energy photons are transmitted to lower band gap layers.
ThicknessOn increasing the p-GaN thickness, generated charge carriers are not separated out instead they start recombining in p-region which results in decrease in the Jsc as shown in fig. (a).
DopingWe also investigated the effect of doping by taking different doping concentration. Results shows that Jsc first increases and then decreases with increase in doping concentration, as shown in fig. (a).
Preliminary design: i-region thicknessIt can be observed that Jsc increases with increasing i-layer thickness. Since i-layer is low bandgap semiconductor compare to p-GaN, it can absorb the photons of some lesser energy than p-GaN.
There is no significant change in the Fill Factor(FF). However, FF starts to decrease as we increase the thickness because series resistance of the cell also increases with increasing thickness of i-layer
Jsc of the double hetero-junction GaN/InGaN solar cell increases with increase in indium composition till 20%, which contributes to increase in efficiency but beyond this composition Jsc decreases sharply as shown in Figure.
low temperature nucleation layer growth at 550 oC high temperature GaN growth at 1060 oC, lateral growth, and surface roughening which induce a lightly drop in the reflectance intensityisland coalescence which the amplitude and intensity of oscillations increases, qusi-2D GaN growth (500torr)qusi-2D GaN growth
(c) low temperature nucleation layer growth at 550 oC (d) temperature ramp and morphology transformation(e) high temperature GaN growth at 1060 oC, lateral growth, and surface roughening which induce a lightly drop in the reflectance intensity(f) island coalescence which the amplitude and intensity of oscillations increases, qusi-2D GaN growth (500 torr)(g) qusi-2D GaN growth
ConclusionIndium Gallium Nitride is a semiconductor material with potential to be used in photovoltaic devices.
Established InGaN as a high-efficiency photovoltaic material.
p-i-n double hetero junction structure is optimized with conventional structure and also effect of indium variation is observed on characteristic parameters.
ReferencesNeff, H., Semchinova, O., Lima, A., Filimonov, A., Holzhueter, G.,“Photovoltaic properties and technological aspects of In1-xGaxN/Si, Ge(0 < x < 0.6) heterojunction solar cells,” Sol. Energy Mater. Sol. Cells 90, 982-997(2006).Jani, O.et al., “Design and characterization of GaN/InGaN solar cells,” Appl. Phys. Lett. 91, 132117 (2007).Shih-Wei Feng et al., “Theoretical simulations of the effects of the indium content, thickness, and defect density of the i -layer on the performance of p - i - n InGaN single homojunction solar cells ” Appl. Phys. Lett. 108, 093118 (2010).Iulian Gherasoiu et al., “Photovoltaic action from InxGa1-xN p-n junctions with x > 0.2 grown on silicon ” Phys. Status Solidi C 8, No. 7–8, 2466–2468 (2011).
AcknowledgmentI am thankful to the Director, CSIR-CEERI, Pilani for giving me opportunity to work in this laboratory.
I am thankful to my supervisor Mr. Sonachand Adhikari.
I am also thankful to Dr. C. Dhanvantri (Group Leader-ODG), Dr. S. Pal and Dr. Sumitra Singh for constant encouragement in this work. I also thank all ODG members for their support.
I am thankful to training in-charge Mr. Vinod K. Verma.