Electrical Contact to a Transparent Conductor: Gallium Oxide Issue: Forming a bi-directional metal contact to Ga 2 O 3 Science: Metal – oxide reaction controls interface current Best Option: Ti. Low work function, forms lower band gap oxide Nanoscopic Mechanism: Measure interface reaction with electron Macroscopic Response: Measure current-voltage characteristics Energy Filled states Empty states metal oxide No states vacuum No Reaction unction Forward Bias Current Flow Reverse Bias No current N i P d N i P d N i P d Ga 2 O 3 Ga 2 O 3 Ga 2 O 3 For current to flow, electrons in filled states need empty states to move into, also, no energy barriers in Ni and Pd Less stable oxide than Ga – No Reaction Large work function – Rectifying Contact TiO 2 Ti-Ga Ga Ga 2 O 3 (Al,Ga) Ti and Al: More stable oxide than GA – Reaction Small work function – Contact depends on reacted oxide Smaller gap TiO 2 – bi-directional current Larger gap Al 2 O 3 – Rectifying, lower barrier than Ni
Electrical Contact to a Transparent Conductor: Gallium Oxide
Feb 22, 2016
Electrical Contact to a Transparent Conductor: Gallium Oxide Marjorie A. Olmstead, University of Washington, DMR 1104628 am. Issue: Forming a bi-directional metal contact to Ga 2 O 3 Science: Metal – oxide reaction controls interface current - PowerPoint PPT Presentation
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Electrical Contact to a Transparent Conductor: Gallium OxideMarjorie A. Olmstead, University of Washington, DMR 1104628
amIssue: Forming a bi-directional metal contact to Ga2O3
Science: Metal – oxide reaction controls interface currentBest Option: Ti. Low work function, forms lower band gap oxide
Nanoscopic Mechanism:Measure interface reaction with electron spectroscopy
Macroscopic Response:Measure current-voltage characteristics
Ener
gy
Filled states
Empty states
metal oxide
No states
vacu
um
No Reaction
LargeWorkFunction
Forward BiasCurrent Flow
Reverse Bias
No current
NiPd
NiPd
NiPd
Ga2O3
Ga2O3
Ga2O3
For current to flow, electrons in filled states need empty states to move into, also, no energy barriers in either direction.
Ni and Pd Less stable oxide than Ga – No ReactionLarge work function – Rectifying Contact
TiO2Ti-Ga Ga2O3 Ga2O3
(Al,G
a)2O
3
Ti and Al: More stable oxide than GA – ReactionSmall work function – Contact depends on reacted oxide
Smaller gap TiO2 –bi-directional currentLarger gap Al2O3 –Rectifying, lower barrier than Ni
Visiting pulsed laser deposition laboratory
NSF P. I. Olmstead mentors high school students to organize and run a weekly “Math and Engineering” club at their former elementary school in conjunction with the Seattle Parks and Recreation Department. The thirty 90-minute sessions ranged from logic puzzles to hovercrafts, all using inexpensive, easily obtained materials. The teens taught principles of engineering design and mathematical concepts to 3rd – 5th graders, while also serving as role models.
Community Engagement at Home and AbroadMarjorie A. Olmstead, University of Washington, DMR 1104628
Elementary Math and Engineering Club
Above: Students perfect their ping-pong ball catapults with their high school mentor
Twenty STEM high school students from the Midorigaoka High School, Japan, visited UW-Materials Science and Engineering in January 2012, as a part of the 2011 Japan’s Earthquake Recovery Act. NSF Co-P.I. Fumio Ohuchi hosted their visit to his laboratories, and gave a lecture on NSF-sponsored research.
Below: Visiting Japanese students with their new American friends.
Japanese Teens Experience US Campus & Research
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