Study of dry etching for GaN and InGaN-based laser structure using inductively coupled plasma reactive ion etching

Abstract

Dry etching of undoped, n-GaN, p-GaN and InGaN laser structure was investigated by inductively coupled plasmas reactive ion etching (ICP-RIE) using Ni mask. As Cl-2/Ar gas flow rates were fixed at 10/25 sccm, the etched surface roughness has the lowest value of 0.2 nm at constant ICP/bias power = 300/100 W and 5 mTorr chamber pressure for undoped GaN. The highest etching rate of 12,000 Angstrom/min for n-GaN was achieved at 30 mTorr, 300 W ICP, 100 W bias power using low Cl-2 flow rate (Cl-2/Ar = 10/25 sccm) gas mixtures. The surface roughness was dependent of bias power and chamber pressure, and shows a low root mean square (rms) roughness value of about I nm at 50 W of bias power for n-GaN and p-GaN. For etching of InGaN laser structure using high O-2 flow rate (Cl-2/Ar = 50/20 sccm) and low chamber pressure 5 mTorr, a smooth mirror-like facet of InGaN laser diode structure was obtained. Using these etching parameters, mirror-like facets can be obtained which can be used for the fabrication of nitride-based laser diodes. Moreover, at the fixed Cl-2/Ar flow rate of 10/25 sccm, ICP/bias power of 200/100 W and chamber pressure of 30 mTorr, the InGaN-based materials nanorods were fabricated with a density of about 10(8) cm(-2) and dimension of 50-100 nm. (C) 2004 Elsevier B.V. All rights reserved.