Ga2O3/GaN heterostructural ultraviolet photodetectors with exciton-dominated ultranarrow response

Ultraviolet photodetectors have demonstrated a wide range of applications, e.g., missile launching, tracking detection, environmental monitoring, etc. This Article presents an ultraviolet photodetector based on a Ga2O3/GaN heterostructure that is equipped with tunable multiband detectivity via bias voltage and a record ultranarrow response. Particularly, this spectral response can be tuned from ultraviolet-C to ultraviolet-A by modulating the depletion region of the photodetector via adjusting bias. Under a higher bias, a photoresponse with a full-width at half-maximum of ∼4 nm at 363 nm is achieved. This ultranarrow response reaches 2.58 × 103 A/W and an external quantum efficiency of (8.84 × 105)% under 28 V bias. The photoluminescence, photoluminescence excitation, and light-absorption measurements suggest that this ultranarrow-band detectivity can be ascribed to the field-enhanced exciton ionization process in the GaN layer. The high responsivity can be attributed to the internal gain of the photodetector originating from the relatively large valence band offset between the Ga2O3 and GaN layers. This work provides a promising approach to the development of high-performance and versatile multiband ultraviolet photodetectors with electrical tunability. It is also worth highlighting that the features of inexpensive manufacturing and easy scalability are particularly attractive for mass production.