Assessment of GaN metal–semiconductor–metal photodiodes for high-energy ultraviolet photodetection

Abstract

We report on the fabrication and characterization of low dark-current GaN metal-semiconductormetal ͑MSM͒ photodiodes. Their quantum efficiency in the vacuum-ultraviolet range has been analyzed, demonstrating that these devices are an excellent choice for high-energy photodetection. Models to explain and control the performance as a function of residual doping and geometry are applied to GaN-based MSM photodiodes.

High responsivity in molecular beam epitaxy grown β-Ga2O3 metal semiconductor metal solar blind deep-UV photodetector

“…III-nitride alloys (AlGaN), which have been widely explored [12][13][14][15][16] for solar blind UV detection, suffer from lack of native substrates which is a major bottleneck to achieving superior material quality. In contrast, large area single crystal Ga 2 O 3 substrates can be grown from the melt by various conventional crystal growth techniques 17,18 with much superior crystal quality providing an economic and performance advantage.…”

Solar-blind MSM-photodetectors based on Al x Ga1-x N heterostructures

“…The breakdown voltage is mainly determined by the quality of the active layer material. The inhomogeneities at the edges of interdigitated contacts also contribute to a reduction of the breakdown voltage (Monroy et al 2002). At the edges of the contacts the electric filed is much stronger and these MSM-detector regions of highest field are responsible for the beginning of breakdown in a real MSM device.…”

“…For smaller devices with 1.5µm finger separation the breakdown voltage was 50-70 V which results in average breakdown field of ∼300-450 kV/cm between the contacts. The breakdown voltage is equal to 40 V for GaN-based MSM-device with 2 µm finger width and spacing (Monroy et al 2002) and 80 V for Al 0.38 Ga 0.62 N MSM-detector with 10 µm separation between the fingers (Ozbay et al 2004). Thus, the breakdown voltages obtained experimentally are lower than those expected from theoretical electric field strength for the beginning of avalanche.…”

Role of excitons in the persistent photocurrent of GaN‐based MSM detectors

“…Several groups have reported the characterization of photoconductive [3][4][5][6], photovoltaic positiveintrinsic-negative (p-i-n) [7] nitride-based photodetectors and Schottky-based metal-semiconductormetal (MSM) photodetectors [8,9]. In contrast, just a very few papers have been published on the characterization of UV detectors working at temperature as high as 700 K. In this work we have studied the role of excitons in two different low barrier metal-semiconductor-metal (MSM) GaN-based UV photodetectors in the temperature range between 300 K and 700 K, by analyzing the temporal response of the devices to short pulses on the millisecond time scale.…”