Precursor-Confined Chemical Vapor Deposition of 2D Single-Crystalline Se_<i>x</i>Te_1–<i>x</i> Nanosheets for p-Type Transistors and Inverters

Abstract

Two-dimensional (2D) tellurium (Te) is emerging as a promising p-type candidate for constructing complementary metal-oxide-semiconductor (CMOS) architectures. However, its small bandgap leads to a high leakage current and a low on/off current ratio. Although alloying Te with selenium (Se) can tune its bandgap, thermally evaporated Se x Te 1– x thin films often suffer from grain boundaries and high-density defects. Herein, we introduce a precursor-confined chemical vapor deposition (CVD) method for synthesizing single-crystalline Se x Te 1– x alloy nanosheets. These nanosheets, with tunable compositions, are ideal for high-performance field-effect transistors (FETs) and 2D inverters. The preformation of Se–Te frameworks in our developed CVD method plays a critical role in the growth of Se x Te 1– x nanosheets with high crystallinity. Optimizing the Se composition resulted in a Se 0.30 Te 0.70 nanosheet-based p-type FET with a large on/off current ratio of 4 × 10 5 and a room-temperature hole mobility of 120 cm 2 ·V –1 ·s –1, being eight times higher than thermally evaporated Se x Te 1– x with similar composition and thickness. Moreover, we successfully fabricated an inverter based on p-type Se 0.30 Te 0.70 and n-type MoS 2 nanosheets, demonstrating a typical voltage transfer curve with a gain of 30 at an operation voltage of V dd = 3 V.