Impact of Acceptor Concentration on Electronic Properties of n~+-GaN/p~+-SiC Heterojunction for GaN/SiC Heterojunction Bipolar Transistor

摘要

The electrical properties of n~+-GaN/p~+-SiC heterojunction diodes have been investigated by varying the acceptor concentration of p~+-SiC epilayers (N_a) and polytype of SiC (4H- and 6H-SiC). The current-voltage (I-V) characteristics of diodes with N_a ～ 1×10~(19) cm~(-3) were dominated by tunneling-assisted current. The diodes with N_a ～ 1×10~(18) cm~(-3) exhibit excellent characteristics and 6H-SiC may be a better choice from a view point of electron injection into p-SiC base. Compared to previous investigations (N_a < 10~(16)cm~(-3)), we could obtain good rectification with p-SiC doped to two-order-of-magnitude higher acceptor concentration.