Controllable p-type doping for 2D-WSe2 and application in charge trap flash

Abstract

Two-dimensional (2D) materials, due to their ultra-thin geometry, are one of the potential channel materials for future logic and memory chips. However, highly reliable p-type memory devices based on 2D semiconductors such as WSe2 urgently need controllable doping technology to regulate their polarity. Here, we have reported a mild doping method for controlling the type and concentration of majority carriers in the WSe2 channel by surface thermal oxidation in air at 200 °C. By doping ambipolar pristine WSe2 transistors, we have converted them into unipolar p-type transistors with a regular increase in hole concentration by 8.1 × 1012 cm−2. More importantly, the doping states in WSe2 channel have remained unchanged even after 6 months. Compared to the pristine WSe2 devices with limited storage capability, the oxidized WSe2 charge trap flash exhibited an on–off ratio over 104 without any noticeable degradation after 5000 operating cycles. Our findings pave the way for high-performance 2D p-type flash.