Wafer-scale fabrication of two-dimensional beta-In2Se3 photodetectors

TL;DR

This paper demonstrates wafer-scale growth of high-quality 2D beta-In2Se3 films and their integration into photodetectors with superior speed and sensitivity, advancing the potential for commercial 2D optoelectronic devices.

Contribution

It reports the first wafer-scale epitaxial growth of 2D beta-In2Se3 and its successful fabrication into high-performance photodetectors.

Findings

Wafer-scale epitaxial growth of 2D beta-In2Se3 achieved.

Photodetectors show fast response (~7 ms) and high detectivity.

Optical bandgap of 1.38 eV measured.

Abstract

The epitaxial growth of two-dimensional (2D) $\beta-In_2Se_3$ material was obtained over 2-inches c-sapphire wafers using molecular beam epitaxy (MBE). Excellent quality of thick (90 nm) and very thin films, down to two quintuple layers (2 nm), was confirmed by x-ray diffraction (XRD), Raman spectroscopy, and aberration-corrected scanning transmission electron microscopy (ac-STEM). Wafer-scale fabrication of photodetectors based on five quintuple layers was produced using photolithography and other standard semiconductor processing methods. The photodetectors exhibit responsivity of 3 mA/W, peak specific detectivity (D*) of $10^9$ Jones, external quantum efficiency (EQE) of 0.67 % at 550 nm, and response-time of ~7 ms, which is faster than any result previously reported for $\beta-In_2Se_3$ photodetectors. From the photocurrent measurements, an optical bandgap of 1.38 eV was observed. These results on wafer-scale deposition of 2D $In_2Se_3$, as well as its fabrication into optoelectronic devices provide the missing link that will enable the commercialization of 2D materials.