Wafer-scale detachable monocrystalline Germanium nanomembranes for the growth of III-V materials and substrate reuse

TL;DR

This paper introduces the PEELER process for creating wafer-scale, detachable monocrystalline germanium nanomembranes that enable substrate reuse and facilitate the growth of III-V materials, reducing Ge consumption and costs.

Contribution

The novel PEELER process allows for wafer-scale Ge nanomembranes with high crystallinity and surface quality, enabling substrate reuse and integration with III-V materials.

Findings

Successful fabrication of wafer-scale Ge nanomembranes with <1 nm roughness.

Demonstrated high-quality GaAs layer growth on Ge NMs.

Reusability of Ge substrates through chemical reconditioning.

Abstract

Germanium (Ge) is increasingly used as a substrate for high-performance optoelectronic, photovoltaic, and electronic devices. These devices are usually grown on thick and rigid Ge substrates manufactured by classical wafering techniques. Nanomembranes (NMs) provide an alternative to this approach while offering wafer-scale lateral dimensions, weight reduction, limitation of waste, and cost effectiveness. Herein, we introduce the Porous germanium Efficient Epitaxial LayEr Release (PEELER) process, which consists of the fabrication of wafer-scale detachable monocrystalline Ge NMs on porous Ge (PGe) and substrate reuse. We demonstrate monocrystalline Ge NMs with surface roughness below 1 nm on top of nanoengineered void layer enabling layer detachment. Furthermore, these Ge NMs exhibit compatibility with the growth of III-V materials. High-resolution transmission electron microscopy (HRTEM) characterization shows Ge NMs crystallinity and high-resolution X-ray diffraction (HRXRD) reciprocal space mapping endorses high-quality GaAs layers. Finally, we demonstrate the chemical reconditioning process of the Ge substrate, allowing its reuse, to produce multiple free-standing NMs from a single parent wafer. The PEELER process significantly reduces the consumption of Ge during the fabrication process which paves the way for a new generation of low-cost flexible optoelectronics devices.