Carrier Transport Properties in Few-Layer WS0.3Se1.7/(WOx)WS0.3Se1.7 Lateral p+–n Junctions Using a Metal–Oxide–Semiconductor Field-Effect Transistor (MOSFET) Structure

Abstract

The carrier transport properties of lateral p+–n junctions composed of few-layer WS0.3Se1.7/(WOx)WS0.3Se1.7 on thermally grown SiO2 or high-κ amorphous Al0.74Ti0.26Oy dielectric layers on p+-Si substrates were investigated and analyzed using field-effect transistor structures. Plasma-laser irradiation promoted selective oxidation near the few-layer WS0.3Se1.7 surface and improved the rectification behavior of the current–voltage characteristics. A photocurrent current density (Jph) of 4 × 10–7 A/cm2 was recorded for WS0.3Se1.7/(WOx)WS0.3Se1.7 lateral p+–n junctions under simulated solar-light (AM1.5G) irradiation. Subsequently, improved Jph values of 7.1 × 10–6 (∼17 times) and 1.23 × 10–5 A/cm2 (∼30 times) were obtained by inserting a silver (Ag) back-reflector layer between the amorphous Al0.74Ti0.26Oy dielectric layer and p+-Si and an adding an antireflection (AR) layer of SnO2, respectively. In addition, an enhanced Jph of 1.3 × 10–5 A/cm2 was achieved with a Voc of 0.84 V and an FF of 57% upon applying a gate bias of +12 V. Thus, the photonic and electronic design of lateral p+–n junctions composed of few-layer WS0.3Se1.7/(WOx)WS0.3Se1.7 structures contributes to further research on various types of 2D lateral heterostructures for the application in optoelectronic and photovoltaic devices.