Low damage thermally assisted electron cyclotron resonance etch technology for wide bandgap II-VI materials

Abstract

A flexible and low damage dry etch technology for the fabrication of ZnSe-based nanostructures is presented. Thermally assisted electron cyclotron resonance etching using gas mixtures of chlorine compounds and Ar and N2, respectively, combines plasma etching at low ion energies with process temperatures between 60 and 250 °C. With increasing process temperatures, rising etch rates and reduced surface roughness indicate a thermal activation of the etching process. The etch profile can be controlled by varying the plasma power causing a transition from partially physical to prevailing chemical etch properties. High quantum efficiencies in CdZnSe/ZnSe quantum wires with lateral sizes down to 20 nm were obtained, indicating a significantly reduced etch damage compared to conventionally dry etched II-VI nanostructures. The potential of the etch technology is demonstrated by realizing quantum wires with a blue shift of the photoluminescence signal (e.g., 8 meV for 20-nm-wide wires) caused by lateral carrier confinement effects.