Thermal Stability of Strained AlGaN/GaN Heterostructures

The thermal stability of strained AlGaN/GaN heterostructures is characterized by comparing unannealed and 700°C 30-min annealed Ni Schottky contacts prepared on strained AlGaN/GaN heterostructures. Using photoemission, capacitance--voltage measurements, and the self-consistent solution of Schrodinger's and Poisson's equations, it is found that after 700°C 30-min thermal annealing the Schottky barrier height of Ni Schottky contacts on strained AlGaN/GaN heterostructures is increased, and the sheet density of polarization charges and the sheet density of two-dimensional electron gas (2DEG) electrons for the strained AlGaN/GaN heterostructures are reduced. These results are closely related to the performance of AlGaN/GaN HFETs at high temperature.