二硒化钨
掺杂剂
材料科学
接触电阻
兴奋剂
肖特基势垒
过渡金属
钨
电子迁移率
纳米技术
电子转移
晶体管
光电子学
化学物理
化学
光化学
催化作用
冶金
电压
物理
二极管
量子力学
生物化学
图层(电子)
作者
Mahito Yamamoto,Shu Nakaharai,Keiji Ueno,Kazuhito Tsukagoshi
出处
期刊:Nano Letters
[American Chemical Society]
日期:2016-03-10
卷期号:16 (4): 2720-2727
被引量:147
标识
DOI:10.1021/acs.nanolett.6b00390
摘要
Transition metal oxides show much promise as effective p-type contacts and dopants in electronics based on transition metal dichalcogenides. Here we report that atomically thin films of under-stoichiometric tungsten oxides (WOx with x < 3) grown on tungsten diselenide (WSe2) can be used as both controlled charge transfer dopants and low-barrier contacts for p-type WSe2 transistors. Exposure of atomically thin WSe2 transistors to ozone (O3) at 100 °C results in self-limiting oxidation of the WSe2 surfaces to conducting WOx films. WOx-covered WSe2 is highly hole-doped due to surface electron transfer from the underlying WSe2 to the high electron affinity WOx. The dopant concentration can be reduced by suppressing the electron affinity of WOx by air exposure, but exposure to O3 at room temperature leads to the recovery of the electron affinity. Hence, surface transfer doping with WOx is virtually controllable. Transistors based on WSe2 covered with WOx show only p-type conductions with orders of magnitude better on-current, on/off current ratio, and carrier mobility than without WOx, suggesting that the surface WOx serves as a p-type contact with a low hole Schottky barrier. Our findings point to a simple and effective strategy for creating p-type devices based on two-dimensional transition metal dichalcogenides with controlled dopant concentrations.
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