A Schottky-Type Metal-Semiconductor-Metal Al0.24Ga0.76N UV Sensor Prepared by Using Selective Annealing

Abstract

Asymmetric metal-semiconductor-metal (MSM) aluminum gallium nitride (AlGaN) UV sensors with 24% Al were fabricated using a selective annealing technique that dramatically reduced the dark current density and improved the ohmic behavior and performance compared to a non-annealed sensor. Its dark current density at a bias of −2.0 V and UV-to-visible rejection ratio (UVRR) at a bias of −7.0 V were 8.5 × 10−10 A/cm2 and 672, respectively, which are significant improvements over a non-annealed sensor with a dark current density of 1.3 × 10−7 A/cm2 and UVRR of 84, respectively. The results of a transmission electron microscopy analysis demonstrate that the annealing process caused interdiffusion between the metal layers; the contact behavior between Ti/Al/Ni/Au and AlGaN changed from rectifying to ohmic behavior. The findings from an X-ray photoelectron spectroscopy analysis revealed that the O 1s binding energy peak intensity associated with Ga oxide, which causes current leakage from the AlGaN surface, decreased from around 846 to 598 counts/s after selective annealing.

Optical and Electrical Properties of AlGaN-Based High Electron Mobility Transistors and Photodetectors with AlGaN/AlN/GaN Channel-Stacking Structure

“…AlGaN/GaN two-dimensional electron gas (2DEG) structures grown on the SiC substrate had been reported in our previous works. , AlGaN/GaN double-channel structures to improve the transport properties in the HEMT devices had been grown on Al 2 O 3 , , Si, GaN, and SiC , substrates. A high UV-to-visible rejection ratio of AlGaN-based PDs , has been reported. The electroluminescence and PD properties were shown in the Schottky-type p-GaN gate double-channel GaN HEMT structures .…”

Characterizations of AlGaN/GaN Membrane-type Photodetectors

“…The ultraviolet (UV) photodetectors can be used for smoke alarm detectors, solar cells at a short wavelength region, and medical applications . AlGaN-based photodetectors , with a high UV to visible rejection ratio have been reported. The p-GaN/AlGaN/GaN structure with a p-GaN gate and a two-dimensional electron gas (2DEG) channel has been reported for the visible-blind UV photodetectors .…”

“…The flexible visible-blind ultraviolet photodetectors with the 2DEG structure were grown and separated from GaN-on-insulator (GaNOI) wafers . The metal–semiconductor–metal (MSM) GaN , and AlGaN , structures have been reported as UV sensors and photodetectors. The ultraviolet (UV) photodetector with a tungsten oxide gate AlGaN/GaN heterostructure was reported with an integrated microheater …”