In-plane Intramolecular WSe2 p-n Junction Realized by Combination of Chemically and Electrically Doping

Abstract

The p-n junction is one of the most important basic structures in the semiconductor field, with vast applications in photodetectors, transistors, light emitting diodes, and solar cells. Here, an new in-plane intramolecular WSe2 p-n junction is realized, in which the n-type region and p-type region are chemically doped by polyethyleneimine and electrically doped by the back-gate, respectively. An ideal factor of 1.66 is achieved, proving the high quality of the p-n junction realized by this method. As a photovoltaic detector, the device possesses a responsivity of 80 mAW-1 (≈20% external quantum efficiency), a specific detectivity of over 1011 Jones and fast response features (200 μs rising time and 16 μs falling time) at zero bias, simultaneously. Moreover, a large open-circuit voltage of 0.38 V and an external power conversion efficiency of ≈1.4% realized by the device also promises its potential in microcell applications.