Large-size free-standing single-crystal β-Ga2O3 membranes fabricated by hydrogen implantation and lift-off

Abstract

In this paper, we demonstrated large-size free-standing single-crystal β-Ga₂O₃ NMs fabricated by the hydrogen implantation and lift-off process directly from MOCVD grown β-Ga₂O₃ epifilms on native substrates. The optimum implantation conditions were simulated with a Monte-Carlo simulation method to obtain a high hydrogen concentration with a narrow ion distribution at the desired depth. Two as grown β-Ga₂O₃ samples with different orientations ([100] and [001]) were used to successfully create 1.2 μm thick β-Ga₂O₃ NMs without any physical damage. These β-Ga₂O₃ NMs were then transfer-printed onto rigid and flexible substrates such as SiC and polyimide substrates. Various material characterization studies were performed to investigate their crystal quality, surface morphologies, optical properties, mechanical properties, and bandgaps before and after the lift-off and revealed that the good material quality was maintained. This result offers several benefits in that the thickness, doping, and size of β-Ga₂O₃ NMs can be fully controlled. Moreover, more advanced β-Ga₂O₃-based NM structures such as (Al_xGa_1−x)₂O₃/Ga₂O₃ heterostructure NMs can be directly created from their bulk epitaxy substrates; thus this study provides a viable route for the realization of high performance β-Ga₂O₃ NM-based electronics and optoelectronics that can be built on various substrates and platforms.