Self-assembly of a lateral quasi-Ohmic CuInSe₂/InSe isotype heterojunction for flexible devices by pulsed laser deposition

The contacts between two-dimensional InSe films and metal electrodes play an important role in nanoelectronics flexible devices. Generally, there is a large work function difference between the Au and InSe films, which would form a Schottky contact to deteriorate device performances. Herein, we designed a lateral self-assembled CuInSe₂/InSe isotype heterojunction on a flexible mica substrate by pulsed laser deposition, which could improve the contact performances between electrodes and InSe films. By combining the X-ray photoelectron spectroscopy and Kelvin probe force microscopy results, the In rich CuInSe₂ and InSe regions could act as quasi-n⁺-n junctions for reduction of the contact resistance with electrodes. Compared to the InSe films with Au electrodes, the CuInSe₂/InSe isotype heterojunction presents approximately half channel resistance and four times photocurrent values. Moreover, the heterojunction devices can still maintain relatively good performance under bending states by restraining the dark current. The present work proves the potential of CuInSe₂/InSe isotype heterojunctions for flexible applications.