Selective etching of (111)B-oriented $Al_x Ga_{1-x} As$-layers for epitaxial lift-off

TL;DR

This study investigates the selective etching of (111)B-oriented AlGaAs layers with varying aluminum content and thickness for epitaxial lift-off, demonstrating high-quality transfer of GaAs membranes for nonlinear optical applications.

Contribution

It provides a comparative analysis of etching behaviors of (111)B-oriented layers versus standard orientations, enabling improved fabrication of GaAs nanostructures.

Findings

Thinner sacrificial layers and lower aluminum content reduce lateral etch rates.

(111)B-oriented layers exhibit similar etch rates to (100) orientations with some differences.

High-quality GaAs membranes are successfully transferred and nano-patterned.

Abstract

GaAs-(111)-nanostructures exhibiting second harmonic generation are new building blocks in nonlinear optics. Such structures can be fabricated through epitaxial lift-off employing selective etching of Al-containing layers and subsequent transfer to glass substrates. In this article, the selective etching of (111)B-oriented $Al_x Ga_{1-x}As$ sacrificial layers (10 nm to 50 nm thick) with different aluminum concentrations (x=0.5 to 1.0) in 10 % hydrofluoric acid is investigated and compared to standard (100)-oriented structures. The thinner the sacrificial layer and the lower the aluminum content, the lower the lateral etch rate. For both orientations, the lateral etch rates are in the same order of magnitude, but some quantitative differences exist. Furthermore, the epitaxial lift-off, the transfer, and the nano-patterning of thin (111)B-oriented GaAs membranes is demonstrated. Atomic force microscopy and high-resolution x-ray diffraction measurements reveal the high structural quality of the transferred GaAs-(111) films.