Observing near-infrared/ultraviolet responses within GaN/AlN superlattice for dual-band detection

Dual-band photodetectors operating within infrared (IR) and ultraviolet (UV) wavelength ranges are highly applicable for tracking and surveillance of targets applications. Because of the large band-gap and conduction band offset, nitride heterostructures are good candidates for monolithically integrated IR and UV dual-band detection. However, suffering from the considerable lattice mismatch and strong polarization effect of nitride heterostructures, photodetectors with complicated structures increase the difficulties of material epitaxy and device fabrication. Here, we present a relatively simple structure design for the detection of IR and UV signals on the same sensing area simultaneously. The responses of IR and UV signals originate from the intersubband and interband transitions in the GaN/AlN superlattice sandwiched by n-doped GaN contact layers, respectively. Experimental results show that the grown sample exhibits an absorption response peaked at 1.5 μm for TM-polarized input lights. Meanwhile, the prototype sample also has a strong photocurrent response at wavelengths shorter than 350 nm, which is mainly decided by the band-gap of the GaN/AlN superlattice. These results prove the feasibility of the proposed structure of detecting IR and UV dual-band signals.