Self-powered ultraviolet photodetection realized by GaN/Si nanoheterostructure based on silicon nanoporous pillar array

Using silicon nanoporous pillar array (Si-NPA) as substrate, a kind of GaN/Si nanoheterostructure (GaN/Si-NPA) is prepared by depositing GaN nanocrystallites on Si-NPA with chemical vapor deposition method. The morphology characteristics and optical properties of GaN/Si-NPA are investigated systematically. Based on GaN/Si-NPA, a self-powered ultraviolet (UV) photodetector (PD) with device structure of ITO/GaN/Si-NPA/ sc -Si/Ag is constructed by depositing ITO on GaN layer and silver on single crystal silicon , respectively. At zero bias voltage without an external power supply, GaN/Si-NPA exhibits a responsivity of 0.072 mA/W, a high current on/off ratio of ∼10 4 (16 μW/cm 2 ) and fast response speeds of 39.98/40.10 ms under an UV light irradiation at 305 nm. The high performance of GaN/Si-NPA is attributed to the built-in electric field in the heterojunction , which is interpreted via building the energy-band diagrams. The results illustrate that GaN/Si-NPA might be a suitable material system for self-powered UV PDs.