Optimization for the growth condition of in situ SiN _xcap layer on ultrathin barrier InAlGaN/GaN heterostructures by metal-organic chemical vapor deposition

We investigate the dependence of material and electrical properties on the growth temperature of in situ SiN x on InAlGaN/GaN heterostructures grown by metal-organic chemical vapor deposition. Degradation of the interface between SiN x and InAlGaN layer was observed when growth temperature is below 900 °C or above 1100 °C. With the optimized SiN x growth temperature, the high-quality SiN x and low interface trap density can be realized. Thus, the double-sweep capacitance-voltage measurement showed a sharp transition from charge accumulation to depletion with low hysteresis of 0.09 V. A small threshold-voltage shift after gate bias stress (1001 s) was also characterized by I-V measurement.