GaN-Based Double-Heterojunction Bipolar Transistors With a Composition Graded p-InGaN Base

influence of energy band structure on the electrical characteristics of GaN-based double-heterojunction bipolar transistors (DHBTs) has been stud-ied through both simulation and fabrication. According to the simulation result, a novel DHBT structure with a composition graded base was grown and fabricated. A long minority carrier lifetime of 4.08 ns has been achieved for the composition graded p-InGaN base with a greatly improved material quality. The indium composition grading of the p-InGaN base layer combined with Si doping profile tuning for the collector layer was proposed to eliminate the energy barrier usually formed at the conventional GaN/InGaN/GaN base-collector (B-C) junction interface due to the band discontinuity and polarization effect. As a result, the as-fabricated DHBT presents a high intercept voltage of 225 V extracted from the I-C-V-CE curves and a high current gain of 49.

Automated summary

The influence of energy band structure on the electrical characteristics of GaN-based DHBTs was studied through simulation and fabrication. A novel DHBT structure with a composition graded base was grown and fabricated, achieving a long minority carrier lifetime of 4.08 ns. The elimination of the energy barrier at the conventional GaN/InGaN/GaN B-C junction interface was proposed by combining indium composition grading of the p-InGaN base layer and Si doping profile tuning for the collector layer. The as-fabricated DHBT presented a high intercept voltage of 225 V and a high current gain of 49.