Many-body Interactions in Halide-assisted CVD Grown WSe2 for High Performance Photodetectors

Practical device applications of semiconducting two-dimensional (2D) materials based devices rely on their large area growth using Chemical Vapor Deposition (CVD) method. Controlled CVD growth of tungsten diselenide (WSe2) is often challenging because of the high sublimation point of tungsten. In this work, we used NaCl with tungsten oxide to allow the growth of monolayer (1L) WSe2 at a temperature (T) of ~ 750°C. Additionally, we utilized T-dependent PL spectroscopy to analyse the dynamics of excitons, trions and localized excitons states in 1L WSe2. Moreover, we fabricated Al/WSe2 based photodetector (PD) which show a high responsivity of ~ 502 A/W. The frequency-dependent capacitance response of the PD was also analyzed from which an interface trap density Dit was computed to be ~ 3.45 × 10¹² cm^-2 eV^-1; this is the lowest Dit value reported for WSe2-based devices to date. The results obtained in this work reveals great potential of WSe2 for electronic, opto-electronic device applications.