High-Performance p-WSe2/p-Si Isotype Heterojunction Photodetector with Ultra High Detectivity and Responsivity

A p-p isotype heterojunction photodetector was fabricated using a p-type Si substrate and p-type monolayer WSe2 synthesized via chemical vapor deposition (CVD). The heterojunction of WSe2 and Si results in the accumulation of electrons on WSe2 and holes on the Si side, thereby creating an internal electric field. And combination of both materials, which are p-type, results in a notable reduction in recombination in the depletion region, thereby markedly enhancing the photodetection capabilities. The photodetector is capable of detecting light in the wavelength range of 400 to 1550 nm, with a high responsivity of 568 A/W at 532 nm and an external quantum efficiency (EQE) of 1.331 x 10^5 %. Furthermore, the device exhibits a high On/Off ratio of 2.811 x 10^4 and an ultra-high detectivity of 2.075 x 10^15 Jones, due to a minimized dark current of 5 nA. Furthermore, the internal electric field generated by the heterojunction contributes to excellent photovoltaic behavior at open circuit voltage (Voc), rendering it highly suitable for Internet of Things (IoT) and wearable devices. The promising results of these p-WSe2/p-Si heterojunction devices indicate significant potential for next-generation photodetectors.