High-performance solar-blind photodetectors based on Al(x)Ga(1-x)N heterostructures

• Published in: IEEE journal of selected topics in quantum electronics Vol. 10; no. 4; pp. 742 - 751
• Main Authors: Ozbay, E, Biyikli, N, Kimukin, I, Kartaloglu, T, Tut, T, Aytur, O
• Format: Journal Article
• Language: English
• Published: 01-07-2004
• ISSN: 1077-260X
• DOI: 10.1109/JSTQE.2004.831681

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 3fA, leakage currents at 6-V reverse bias were measured on p-i-n samples. The excellent current-voltage (I--V) characteristics led to a detectivity performance of 4.9x10/14/ cmHz(1)2/W(-1). The MSM devices exhibited photoconductive gain, while Schottky and p-i-n samples displayed 0.09 and 0.11 A/W peak responsivity values at 267 and 261 nm, respectively. A visible rejection of 2x10(4) was achieved with Schottky samples. High-speed measurements at 267 nm resulted in fast pulse responses with greater than gigahertz bandwidths. The fastest devices were MSM photodiodes with a maximum 3-dB bandwidth of 5.4 GHz.