Electron Overflow to the AlGaN p-Cladding Layer in InGaN/GaN/AlGaN MQW Laser Diodes
Kay Domen , Reiko Soejima, Akito Kuramata , Toshiyuki Tanahashi
Fujitsu Laboratories Ltd.
This article was received on Wednesday, December 24, 1997 and
accepted on Thursday, January 29, 1998. Abstract
Current
flow through an InGaN/GaN/AlGaN multi-quantum well (MQW) laser diode is
simulated. We found that electron overflow to the AlGaN p-cladding layer is
very large, which prevents the current injection into the MQW layers. We
clarified that the electron overflow occurs easily in nitride lasers because of
three intrinsic reasons; poor hole injection due to the small hole mobility and
thermal velocity, the small conduction band offset for InGaN/GaN, and the high
threshold carrier density. We show that the Al composition and the p-doping of
the AlGaN p-cladding layer is of critical importance to obtain laser
oscillation by current injection. 
