Control of Defects in Aluminum Gallium Nitride ((Al)GaN) Films on Grown Aluminum Nitride (AlN) Substrates
Director s Research Initiative
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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We present efforts aimed at establishing a multiscale approach for simulating dislocations in aluminum gallium nitride AlGaN semiconductors. We performed quantum mechanical and classical molecular dynamics MD simulations to study the electronic and atomic structure of threading edge and screw dislocations in AlGaN, focusing on the structure of the dislocation core and the electrical activity of dislocations, and estimating dislocation velocities as a function of applied stress and temperature. We used the calculated mobility functions from MD to study different junction configurations using a discrete dislocation dynamics DDD simulator, ParaDiS. Finally, we predicted the most likely slip planes in wurtzite AlGaN semiconductors based on general crystallographic principles. The most important results are 1 aluminum Al atoms do not segregate to the dislocation core and atoms in the dislocation core do not produce any defect levels in the bandgap 2 we performed first time classical MD calculations of dislocation velocity as a function of applied stress for three slip systems in gallium nitride GaN 3 we adapted ParaDiS to simulate wurtzite semiconductors and 4 the plane strain produced by the lattice mismatch during growth on the 0001 plane does not create a shear stress on the basal or prismatic planes, hence the operational slip plane must be a pyramidal plane, the most probable being the 1311bar over 2311bar over 22 slip system.
- Electrical and Electronic Equipment
- Atomic and Molecular Physics and Spectroscopy