Using 2D finite element modeling with the ability to solve the current continuity equations, carrier energy transport equation, Schrödinger and Poisson equations self-consistently, as well as the scalar wave equation for waveguiding devices, we have investigated the possible improvements of the device efficiencies by introducing transparent p-type contacts and multiple quantum shells (MQSs) in GaN / In_0.14Ga_0.86N / GaN / p-AlGaN / p-GaN core/multishell nanowires (CMS NWs). The addition of a transparent p-type current spreading contact was found to promote more uniform current injection into the CMS NWs, thus increasing the current injection efficiency. Despite the inclusion of a transparent ptype contact, the current density remained non-uniform and weighted towards the n-contact side of the NW. This asymmetry in the current density was found to be more important for higher injection current whereas it becomes much more uniform with decreasing injection current. Light generation with the transparent contact was found to become more uniformly distributed along the CMS NW, leading to more even light generation within the device in comparison to NWs without transparent p-type contacts. The replacement of single quantum shells (SQS) by MQSs in the active region of the nitride CMS NW-as has been used for conventional InGaN high brightness LEDs (HB-LEDs)-was found to be advantageous up to three quantum shells, increasing light generation from 80.47 to 94.04 W/m under a 4V bias.

Date Published: 25 August 2008
PDF: 9 pages
Proc. SPIE 7056, Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II, 70560X (25 August 2008); doi: 10.1117/12.794979

Published in SPIE Proceedings Vol. 7056:
Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications II
Shizhuo Yin; Ruyan Guo, Editor(s)