Low-temperature fabrication of amorphous carbon films as a universal template for remote epitaxy

TL;DR

This study demonstrates a low-temperature plasma-enhanced chemical vapor deposition method to create ultrathin amorphous carbon layers on various semiconductors, serving as universal templates for high-quality remote epitaxy of multiple III-V materials.

Contribution

It introduces a universal, low-temperature fabrication process for amorphous carbon templates enabling high-quality remote epitaxy on temperature-sensitive substrates.

Findings

Achieved ultra-smooth, monolayer amorphous carbon films with roughness ≤ 0.3 nm.

Successfully grew high-quality, single-crystalline III-V epitaxial layers.

Demonstrated layer lift-off using a Ni stressor.

Abstract

We report on the low-temperature fabrication (300$\deg$C) of ultrathin 2D amorphous carbon layers on III-V semiconductors by plasma-enhanced chemical vapor deposition as a universal template for remote epitaxy. We present growth and detailed characterization of 2D amorphous carbon layers on various host substrates and their subsequent remote epitaxial overgrowth by solid-source molecular beam epitaxy. We present the fabrication of ultra-smooth monolayer thick amorphous carbon layers with roughness $\leq 0.3$ nm determined by atomic-force microscopy and X-ray reflectivity measurement. We show that precisely tailoring the carbon layer thickness allows superior tunability of the substrate-layer interaction. Further, X-ray photoelectron and Raman spectroscopy measurements reveal predominantly sp$^2$-hybridised carbon in the amorphous layers. We observe that a low-temperature nucleation step is favorable for nucleation of III-V material growth on substrates coated with thin amorphous carbon layers. Under optimized preparation conditions, we obtain high-quality, single-crystalline, (001)-oriented GaAs, cubic-AlN, cubic-GaN and In(x)Ga(1-x)As, respectively, and various carbon-coated (001)-oriented substrates as GaAs, InP and 3C-SiC. Transmission electron microscopy images of the substrate-carbon-layer interface reveal a stretching of the atomic bonds at the interface and high-resolution X-ray diffraction measurements reveal high crystal quality and low dislocation densities $<1\times 10^7 \text{cm}^{-2}$. Our results show the universality of our carbon deposition process to fabricate templates for remote epitaxy, e. g., for remote epitaxy on temperature sensitive substrates like GaAs or InP and growth of metastable phases. Lift-off of layers from their substrates is demonstrated by employing a Ni stressor.