Back illuminated AlGaN solar-blind photodetectors

Abstract

We report the growth, fabrication, and characterization of AlxGa1−xN (0⩽x⩽0.60) heteroepitaxial back-illuminated solar-blind p-i-n photodiodes on (0001) sapphire substrates. The group III-nitride heteroepitaxial layers are grown by low-pressure metalorganic chemical vapor deposition on double polished sapphire substrates using various growth conditions. The back-illuminated devices exhibit very low dark current densities. Furthermore, they exhibit external quantum efficiencies up to 35% at the peak of the photoresponse (λ∼280 nm). Improvements were made to the growth technique in order to achieve crack-free Al0.4Ga0.6N active regions on a thick Al0.6Ga0.4N window layer and to obtain activated p-type Al0.4Ga0.6N layers.

High Quantum Efficiency AlGaN/GaN Solar-Blind Photodetectors Grown by Metalorganic Chemical Vapor Deposition

“…Fabrication The fabrication of the p-i-n diodes employs standard processing steps that we have developed earlier [1][2][3][4]. First, the Mg acceptor atoms are activated using rapid thermal annealing in N 2 at 850 ºC for 10 min.…”

“…The metal-semiconductor-metal (MSM) device is well suited for this application, as it is relatively simple to fabricate and its low capacitance can result in a fast response time. Advances in material growth have resulted in high aluminum composition and crack-free AlGaN heterostructures for use as solarblind p-i-n photodetectors [1]. The p-i-n device has the advantage of operating at zero to low bias, eliminating the requirement for a bulky power supply.…”

Solar blind detectors based on AlGaN grown on sapphire

“…Hence, the pixels have to be illuminated from the back side and all layers between the back side and the active region must be transparent at wavelengths around 290 nm. Solar blind detectors grown on a thick transparent (so called window layer) AlGaN layer transparent at 290nm have been fabricated and demonstrated in back side illumination [6,9] although with a limited rejection ratio due to the top p:GaN layer [10]. A 256×256 focal plane array was fabricated leading to the first demonstration of solar blind imaging based on nitrides [11].…”

Al x Ga1-x N solar-blind photodetectors grown by low pressure MOCVD

“…III-V nitrides have recently attracted great interest for applications such as high temperature and high power microelectronic devices [1][2][3][4][5][6][7][8], ultraviolet (UV) lightemitting devices (LEDs) [9][10][11][12][13] and UV photodetectors [14][15][16][17][18]. UV photodetectors are a subject of increasing interest due to a variety of current and potential applications in the military, industrial and scientific areas.…”