Molecular beam epitaxy for high‐efficiency nitride optoelectronics

Abstract

We review the significant progress made in the development of nitride laser diodes by molecular beam epitaxy (MBE). We report on our recent result of room temperature continuous-wave operation of InGaN quantum well laser diodes grown by MBE. Ridge waveguide lasers fabricated on freestanding GaN substrates have a continuous-wave threshold current of 125 mA, corresponding to a threshold current density of 5.7 kA cm -2. The lasers have a threshold voltage of 8.6 V and a lifetime of several minutes. We outline the further technical challenges associated with demonstrating lifetimes of several thousand hours and present an assessment of the potential of MBE as a growth method for commercial quality nitride optoelectronic devices.

Comparison of gain in group-III-nitride laser structures grown by metalorganic vapour phase epitaxy and plasma-assisted molecular beam epitaxy on bulk GaN substrates

“…MBE as a growth technique characterized by ultra-high purity source materials, a reduced point defect density, a precise and accurate doping profile and atomically flat single layer growth seems to be a promising alternative for the growth of group-IIInitride-based devices claiming its position on the cutting edge of semiconductor technology related to this material system. It was demonstrated recently that high-quality 0268-1242/07/070736+06$30.00 © 2007 IOP Publishing Ltd Printed in the UK device structures with a InGaN-based active region operating at room temperature in the continuous-wave (CW) regime can be grown by MBE either with [1] or without [2] ammonia at temperatures as low as 600 • C. Plasma-assisted MBE (PAMBE) enables an ammonia-free step-flow growth mode [3]. High-quality growth is crucial for the active region and its amplification features establishing optical gain necessary to sustain lasing action.…”