High Critical Electric Field Exceeding 8 MV/cm Measured Using an AlGaN p-i-n Vertical Conducting Diode on n-SiC Substrate

摘要

We have succeeded in obtaining the high critical electric field exceeding 8 MV/cm measured using an AlGaN p-i-n vertical conducting diode on n-SiC substrate grown by low-pressure metal organic vapor phase epitaxy. The critical electric field of AlGaN with Al composition of 57% is as high as 8.1 MV/cm, the highest among semiconductors with a doping concentration of less than 10~(17) cm~(-3), at which the avalanche multiplication process takes place. The critical electric field is proportional to the bandgap energy to a power of 2.7. In the forward current-voltage characteristics, the on-state resistance of the diode increases with increasing Al composition. Since there is a tradeoff between the breakdown voltage (V_B) and the on-state resistance (R_(on)), the figure of merit V_B~2/R_(on) has its maximum when the Al composition is about 30% and is twice as high as that for GaN-based diodes. This indicates that AlGaN-based electronic devices are more promising for high-power operation than GaN-based ones.