Wafer-Scale Growth of Sb2Te3 Films via Low-Temperature ALD for Self-Powered Photodetector

TL;DR

This paper reports the low-temperature atomic layer deposition growth of high-quality Sb2Te3 films enabling wide-range, self-powered photodetectors with high responsivity, stability, and fast response across visible to near-infrared wavelengths.

Contribution

It introduces a novel low-temperature ALD process for high-quality Sb2Te3 films and demonstrates their integration into self-powered photodetectors with superior performance.

Findings

Wide detection range from 405 nm to 1550 nm.

High responsivity and detectivity of the photodetectors.

Excellent stability and fast response time.

Abstract

In this work, we demonstrate the performance of a silicon-compatible high-performance self-powered photodetector.A wide detection range from visible (405 nm) to near-infrared (1550 nm) light was enabled by the vertical p-n heterojunction between the p-type antimony telluride (Sb2Te3) thin film and the n-type silicon (Si) substrates. A Sb2Te3 film with a good crystal quality, low density of extended defects, proper stoichiometry, p-type nature, and excellent uniformity across a 4-inch wafer was achieved by atomic layer deposition at 80 {\deg}C using (Et3Si)2Te and SbCl3 as precursors. The processed photodetectors have a low dark current (~20 pA), a high responsivity of (~4.3 Ampere per Watt at 405 nm and ~150 milli-Ampere per Watt at ~1550 nm), a peak detectivity of ~1.65*10^14 Jones, and a quick rise time of ~98 us under zero bias voltage. Density functional theory calculations reveal a narrow, near-direct, type-II bandgap at the heterointerface that supports a strong built-in electric field leading to efficient separation of the photogenerated carriers. The devices have long-term air stability and efficient switching behavior even at elevated temperatures. These high-performance self-powered p-Sb2Te3/n-Si heterojunction photodetectors have immense potential to become reliable technological building blocks for a plethora of innovative applications in next-generation optoelectronics, silicon-photonics, chip-level sensing, and detection.