High-performance solar-blind AlGaN photodetectors


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Ozbay E., Tut T. , Biyikli N.

Conference on Quantum Sensing and Nanophotonic Devices II, San-Jose, Costa Rica, 23 - 27 January 2005, vol.5732, pp.375-388 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 5732
  • Doi Number: 10.1117/12.582491
  • City: San-Jose
  • Country: Costa Rica
  • Page Numbers: pp.375-388
  • Keywords: AlGaN, detectivity, heterostructure, high-speed, MSM, photodetector, p-i-n, Schottky, solar-blind, UV, SEMICONDUCTOR-METAL PHOTODETECTORS, I-N PHOTODIODES, SCHOTTKY-BARRIER PHOTODETECTORS, CHEMICAL-VAPOR-DEPOSITION, HIGH QUANTUM EFFICIENCY, MOLECULAR-BEAM EPITAXY, ULTRAVIOLET PHOTODETECTORS, LOW-NOISE, HETEROSTRUCTURE PHOTODIODES, GAN

Abstract

Design, fabrication, and characterization of high-performance Al(x)Ga(1-x)N-based photodetectors for solar-blind applications are reported. Al(x)Ga(1-x)N heterostructures were designed for Schottky, p-i-n, and metal-semiconductor-metal (MSM) photodiodes. The solar-blind photodiode samples were fabricated using a microwave compatible fabrication process. The resulting devices exhibited extremely low dark currents. Below 3 fA leakage currents at 6 V and 12 V reverse bias were measured on p-i-n and Schottky photodiode samples respectively. The excellent current-voltage (I-V) characteristics led to a detectivity performance of 4.9 x 10(14) CmHz(1/2)W(-1). The MSM devices exhibited photoconductive gain, while Schottky and p-i-n samples displayed 0.15 A/W and 0.11 A/W peak responsivity values at 267 nm and 261 nm respectively. All samples displayed true solar-blind response with cut-off wavelengths smaller than 280 nm. A visible rejection of 4 x 10(4) was achieved with Schottky detector samples. High speed measurements at 267 nm resulted in fast pulse responses with > GHz bandwidths. The fastest devices were MSM photodiodes with a maximum 3-dB bandwidth of 5.4 GHz.