Control of Defects in Aluminum Gallium Nitride ((Al)GaN) Films on Grown Aluminum Nitride (AlN) Substrates

Abstract

Sensors and Electron Devices Directorate, ARLApproved for public release; distribution unlimited. ii REPORT DOCUMENTATION PAGEForm Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)February 2013 ARL-TR-6350 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution unlimited. SUPPLEMENTARY NOTES ABSTRACTWe present efforts aimed at establishing a multiscale approach for simulating dislocations in aluminum gallium nitride ((Al)GaN) 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 (Al)GaN 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 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 slip system. iii Contents SUBJECT TERMS