Synthesis of 2D alpha-GeTe Single Crystals and alpha-GeTe/WSe2 Heterostructures with Enhanced Electronic Performance

Two-dimensional (2D) materials have attracted extensive attention due to their important prospects in electronics and optoelectronics. Synthesizing new 2D materials, characterizing their properties, and developing their applications are still important topics. Herein, the synthesis of alpha-GeTe nanoplates on different substrates via the chemical vapor deposition process and the systematical investigation of their structure and electrical properties, is reported. By controlling the synthesis temperature and carrier gas, alpha-GeTe nanoplates, with a lateral dimension up to 30 mu m and a thickness down to 1.2 nm, which corresponds to the thickness of one unit cell, can be obtained on 2D WSe2 substrate. Electrical transport studies show 2D alpha-GeTe nanoplates have an excellent conductivity (9.33 x 10(5) S m(-1)) and an extraordinary breakdown current density (6.1x 10(7) A cm(-2)). Compared with traditional WSe2 transistors with deposited metal electrodes, the WSe2 transistors with the metallic alpha-GeTe nanoplates as van der Waals metal electrodes achieved much better performance, such as higher on-state current (from 7.83 to 23.23 mu A mu m(-1)) and electron mobility (from 16.5 to 75.0 cm(2) V-1 S-1). This study demonstrates an effective pathway to achieve ultrathin 2D materials and provides an accessible strategy to improve the performance of 2D electronic devices.