Elevated-Temperature Annealing Effects on AlGaN/GaN Heterostructures

Abstract

The effect of high-temperature annealing of undoped AlGaN/GaN heterostructures on different substrates was systematically studied between 1100°C and 1230°C. An AlN spacer layer was found to add stability to structures on sapphire substrates. AlGaN/GaN heterostructures on SiC substrates demonstrated excellent robustness for the temperature range studied, maintaining their mobility, sheet resistance, and sheet concentration values, even after annealing. A silicon nitride, SiN x , capping layer was found to assist in minimizing surface roughness during annealing and maintaining the electrical characteristics of the heterostructures. AlGaN/GaN heterostructures on SiC substrates showed a 20% decrease in mobility for uncapped samples compared with SiN x -capped samples.

Effective Suppression of Current Collapse in AlGaN/GaN HEMT With N2O Plasma Treatment Followed by High Temperature Annealing in N2 Ambience

“…The decrease in electron sheet density of sample D is due to the extra long term RTA process. And it has been reported that the high temperature RTA process decreases 2DEG carrier density and mobility [15], [16]. However, the same situation did not occur in sample B.…”