Dual functional modes for nanostructured p-Cu₂O/n-Si heterojunction photodiodes

Many applications require a photodetector (PD) with multiple functional modes. This study demonstrates a dual functional PD with a simple structure that uses a nanostructured p-Cu₂O/n-Si heterojunction. This device features a self-powering characteristic for an open-circuit voltage (V _oc) of 0.5 V and exhibits an external quantum efficiency (EQE) of 3780% at a reverse bias of -5 V. There is a high EQE at low reverse-bias because trapped holes cause charge to be injected from the electrode. The nanostructured p-Cu₂O/n-Si heterojunction also has a high response speed (<10 ms) in the self-powered mode because there is a built-in potential within p-n junction. This study shows that a nanostructured p-Cu₂O/n-Si heterojunction acts as a self-powered PD for reducing power consumption and as a photomultiplication (PM)-type PD with high internal gain.