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.
InGaN alloys have gained considerable interest over the past due to their tunable band gap extending the operation wavelengths of optoelectronic devices to green–red and IR regions. However, the realization of high In-content InGaN materials is still limited by their material properties. Despite encouraging achievements in InGaN based devices, it is difficult to achieve high quality InGaN with high indium composition. Up to now, there are only few reports about high indium content InGaN films, in particular with indium content > 50%.
Successfully grown In-rich InGaN layers with 300 nm thickness and nominally [In] = 70% deposited on GaN template by MBE were comprehensively investigated by highly spatially-resolved cathodoluminescence. The surface morphology has been investigated by atomic force microscope (AFM) and scanning electron microscopy (SEM) and shows grain-like features. The lateral as well as the vertical luminescence distribution yields a detailed insight in the [In] homogeneity. The thick InGaN films, free of droplets, have a quite homogenous emission at 1.035 eV (~1200 nm) laterally with full-width at half maximum of only 68 meV. Determined from the emission peak, the indium composition is about 75%, which is slightly higher than the nominally intended indium composition. The evolution in growth direction will be presented.
AlGaN-based ultraviolet (UV) light sources have recently attracted much research interest due to their potential candidate to replace excimer and mercury lamps. However, their output power is limited by the inefficient p-type doping at high Al composition AlGaN. In this talk, we will report on the electron-beam-pumped UV light sources, where multiple ultrathinGaN wells are used to enhance the internal quantum efficiency and to reach deep UV range such as 230 nm. And UV light source with wavelength varing from 285-232 nm with corresponded output power of 23-160 mW have been achieved under pulse mode.
Conference Committee Involvement (1)
Gallium Nitride Materials and Devices XX
27 January 2025 | San Francisco, California, United States
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