Investigation of Lattice and Thermal Stress in GaN/A1GaN Field-Effect Transistors

摘要

This report describes work performed in support of the program Investigation of Lattice and Thermal Stress in GaN/AlGaN Field-Effect Transistors (Contract No. N00014-05- C-0120) for the period 7/1/06 - 9/30/06. Our overall goal is to understand the role and contribution of residual stress and junction temperature on the degradation of AlGaN/GaN HEMT electrical device characteristics. To execute this goal, electrical stress measurements will be performed on devices with varying residual stress, and under varying conditions. We plan to use the micro-Raman technique to monitor the evolution of residual stress in the active region of the device over time and under quiescent electrical bias. The question of whether a stress relaxation, potentially inducing dislocations, or simply changing the piezoelectric contribution to the 2DEG charge, contributes to device degradation will be investigated. We will seek to understand the influence of junction temperature on the magnitude of the stress at the active junction. The effect of physical, thermal, and electrical stress on device reliability will be investigated.