Optimization and comparison of argon plasma-induced quantum well intermixing using RIE and ICP

Abstract

Summary form only given, as follows. In this paper, a novel quantum well intermixing (QWI) technique using inductively-coupled (ICP) and reactive-ion etcher (RIE). Argon plasma exposure has been developed. The QWI technique was successfully demonstrated on InGaAs/InGaAsP quantum well (QW) material structure. The experiment was conducted and optimized using Taguchi's method, which was the first time such a method has been used for QWI optimization. It is shown that Taguchi's method is effective in optimizing the QWI shift by finding the optimum plasma processing parameters such as gas flow, pressure and discharge power for both ICP and RIE systems. With the optimized process parameters, a maximum shift of 104 nm and 73 nm was obtained from the InGaAs/InGaAsP QW samples by using ICP and RIE respectively. The optimum ICP process parameters for the maximum QWI shift are 100 sccm argon flow rate, 80 mTorr pressure, 480 W radio-frequency (RF) power and 500 W ICP power For RIE, the optimum process parameters are 50 sccm argon flow rate, 30 mTorr pressure and 480 W RF power. The maximum shift is highly dependent on the process parameters. A comparison between QWI using inductively-coupled plasma and reactive-ion etchers is also given. It shows that the process parameters of argon plasma generated in different plasma machines affect the QWI shift differently. Using a simple global discharge model, we found that the measured bandgap shift is strongly dependent on the calculated ion bombardment energy and ion current density at the samples.