Enhancing Responsivity of Porous GaN Metal-Semiconductor-Metal Ultraviolet Photodiodes by Using Photoelectrochemical Etching

Abstract

In this paper porous and as-grown GaN metal-semiconductor-metal photodiodes with Ni contact electrodes were fabricated. Structural and optical properties were studied of the both samples. Both detectors show a sharp cut-off wavelength at 370 nm, with a maximum responsivity of 0.14 A/W and 0.065 A/W achieved at 360 nm for porous GaN and as-grown metal-semiconductor-metal photodetectors, respectively. The metal-semiconductormetal photodiode based on porous GaN shows enhanced twice magnitude of responsivity relative to the as-grown GaN metal-semiconductor-metal photodiode. Enhancement of responsivity can be attributed to the relaxation of stress and reduction of surface pit density in the porous sample. The porous sample showed a significantly low dark current at 5 V as compared to as grown sample.

Investigations on Al2O3-Dielectric Wide-Gap Al0.3Ga0.7N Channel MOS-HFETs with Composite Al2O3/In Situ SiN Passivation

“…High SR performance of 885.6 A W −1 ha −1 s −1 been achieved in the present sample B, which is superior to 737 A W −1 of our previous work 4 and other devices at similar radiation wavelengths. [19][20][21][22]…”

High-Performance Ultraviolet Light Detection Using Nano-Scale-Fin Isolation AlGaN/GaN Heterostructures with ZnO Nanorods

“…The fastest UV PDs of GaN-based metal-semiconductor-metal, p-i-n, or metal Schottky barrier devices [6] have shown extremely high speed (from microseconds to picoseconds) and low-noise capabilities. However, PDs of these GaN-based structures, developed specially to improve the UV response characteristics, exhibit a very low spectral responsivity of less than 1 A/W [8].…”

“…In spite of these promising advantages, the WBG semiconductors have very low electron mobility. Even though noble heterostructures with a very high electron mobility of ~10 6 cm 2 /V·s using a material system such as MgZnO/ZnO [7] have been reported, most of the passive PDs fabricated using conventional WBG semiconductors have very low spectral responsivity [8]. Moreover, the response speeds of PDs based on ZnO or GaN are very slow in general because the photoresponse characteristics depend on the well-known bottle-neck chemisorption process of oxygen at the surface of such materials [9].…”

Antireflective GaN Nanoridge Texturing by Metal-Assisted Chemical Etching via a Thermally Dewetted Pt Catalyst Network for Highly Responsive Ultraviolet Photodiodes

“…4 For GaN, various nanostructures such as nanopillars, 6−8 nanopyramids, 9 nanodomes, 10,11 and porous GaN 12,13 have been fabricated by either dry (plasma) etching 6,7,14,15 or anisotropic wet (chemical) etching. 8,12,13,16 The former method typically involves lithography-patterned 15 or thermally dewetted metal hard mask 6,7,11,14 for subsequent dry etching of GaN. However, it is notable that dry etching of GaN introduces undesirable damages and defects, 17 resulting in a large dark current in photodetectors 18 and leakage current in power devices.…”

“…Compared with the AR coating of layer stacks which requires precise control of the parameters such as refractive index and thickness, AR surface texturing via nanostructures by a top-down etching method exhibits merits such as omnidirectional, broadband AR characteristics, and facile fabrication process . For GaN, various nanostructures such as nanopillars, − nanopyramids, nanodomes, , and porous GaN , have been fabricated by either dry (plasma) etching ,,, or anisotropic wet (chemical) etching. ,,, The former method typically involves lithography-patterned or thermally dewetted metal hard mask ,,, for subsequent dry etching of GaN. However, it is notable that dry etching of GaN introduces undesirable damages and defects, resulting in a large dark current in photodetectors and leakage current in power devices. , On the contrary, such plasma-induced surface damage can be avoided by wet etching.…”