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

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.