NpN-GaN/InxGa1-xN/GaN heterojunction bipolar transistor on free-standing GaN substrate

作者：Lochner Zachary; Kim Hee Jin; Lee Yi Che; Zhang Yun; Choi Suk; Shen Shyh Chiang; Yoder P Doug; Ryou Jae Hyun^*; Dupuis Russell D

来源：Applied Physics Letters, 2011, 99(19): 193501.

DOI：10.1063/1.3659475

Data and analysis are presented for NpN-GaN/InGaN/GaN double-heterojunction bipolar transistors (HBTs) grown and fabricated on a free-standing GaN (FS-GaN) substrate in comparison to that on a sapphire substrate to investigate the effect of dislocations in III-nitride HBT epitaxial structures. The performance characteristics of HBTs on FS-GaN exhibit a maximum collector current density of similar to 12.3 kA/cm(2), dc current gain of similar to 90, and maximum differential gain of similar to 120 without surface passivation, representing a substantial improvement over similar devices grown on sapphire. This is attributed to the reduction in threading dislocation density afforded by using a homoepitaxial growth on a high-crystalline-quality substrate. The minority carrier diffusion length increases significantly owing to not only a mitigated carrier trap effect via fewer dislocations, but also possibly reduced microscopic localized states.

• 出版日期2011-11-7