Precursor-Confined Chemical Vapor Deposition of 2D Single-Crystalline Se<sub><i>x</i></sub>Te<sub>1–<i>x</i></sub> Nanosheets for p-Type Transistors and Inverters
Haoxin Huang, Jiajia Zha, Songcen Xu, Peng Yang, Yunpeng Xia, Huide Wang, Dechen Dong, Long Zheng, Yao Yao, Yuxuan Zhang, Ye Chen, Johnny C. Ho, Hau Ping Chan, Chunsong Zhao, Chaoliang Tan
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.