Few-Layer MoS2/a-Si:H Heterojunction Pin-Photodiodes for Extended Infrared Detection

Few-layer molybdenum disulfide (FL-MoS2) films have been integrated into amorphous silicon (a-Si:H) pin-photodetectors. To achieve this, vertical a-Si:H photodiodes were grown by plasma-enhanced chemical vapor deposition (PE-CVD) on top of large-scale synthesized and transferred homogeneous FL-MoS2. This novel detector array exhibits long-term stability (more than six month) and outperforms conventional silicon-based pin-photodetectors in the infrared range (IR, λ = 2120 nm) in terms of sensitivities by up to ∼50 mAW–1. Photodetectivities of up to ∼2 × 1010 Jones and external quantum efficiencies of ∼3% are achieved. The detectors further feature the additional functionality of bias-dependent responsivity switching between the different spectral ranges. The realization of such scalable detector arrays is an essential step toward pixelated and wavelength-selective sensors operating in the IR spectral range.