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Metal–Semiconductor–Metal Ultraviolet Avalanche Photodiodes Fabricated on Bulk GaN Substrate | IEEE Journals & Magazine | IEEE Xplore

Metal–Semiconductor–Metal Ultraviolet Avalanche Photodiodes Fabricated on Bulk GaN Substrate


Abstract:

We report the first demonstration of a GaN-based planar metal-semiconductor-metal (MSM) ultraviolet (UV) avalanche photodiode (APD). The MSM APD with semitransparent inte...Show More

Abstract:

We report the first demonstration of a GaN-based planar metal-semiconductor-metal (MSM) ultraviolet (UV) avalanche photodiode (APD). The MSM APD with semitransparent interdigitated Schottky electrodes is fabricated on a low-defect-density GaN homoepitaxial layer grown on a bulk GaN substrate by metal-organic chemical vapor deposition. The dislocation density of the GaN homoepilayer characterized by a cathodoluminescence mapping technique is ~ 5 ×106 cm-2. The photodiode exhibits a low dark current density of ~ 1.4 × 10-9 A/cm2 and a high UV-to-visible rejection ratio up to five orders of magnitude under 20-V bias. At high bias, a room-temperature avalanche gain of more than 1100 is achieved under 365-nm UV illumination. The breakdown voltage of the APD shows a positive temperature coefficient of 0.15 V/K, confirming that the high-voltage gain is dominated by the avalanche breakdown mechanism.
Published in: IEEE Electron Device Letters ( Volume: 32, Issue: 9, September 2011)
Page(s): 1260 - 1262
Date of Publication: 14 July 2011

ISSN Information:

Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China

I. Introduction

Gallium-Nitride-Based semiconductor materials have recently attracted much attention in ultraviolet (UV) photodetector applications due to their large direct-bandgap energy, high electron saturation velocity, superior radiation hardness, and high-temperature resistance. In order to detect very weak UV signals, photodiodes with high internal gain and low dark current are greatly needed. To realize high internal gain in GaN-based photodiodes, an avalanche multiplication mechanism offering internal photocurrent gain by impact ionization is the best choice. However, due to the large lattice mismatch between GaN and its foreign substrate like sapphire, a heteroepitaxial GaN film often contains high-density dislocations and other structural defects, which would not only cause high dark current but also lead to a premature microplasma breakdown in the active region of GaN-based avalanche photodiodes (APDs) [1]. To minimize the impact of structural defects, past GaN-based APDs reported often have to employ a small active device area of less than 100 in diameter [2], [3]. A major approach to improve epilayer quality is to develop a GaN homoepitaxy technique. Recently, visible-blind GaN p-i-n APDs with high multiplication gain of more than have been fabricated on a bulk GaN substrate. However, the device reported suffers from an enhanced red shift of the absorption edge due to deep impurity band absorption when its depletion region extends into the p-type layer at high reverse bias [4]. Compared with p-i-n-type photodiodes, metal–semiconductor–metal (MSM) photodiodes offer many attractive advantages for practical applications, such as no p-type doping required, low capacitance, and ease of fabrication and integration. Thus, high-performance GaN-based APDs are expected to be achievable in a planar MSM configuration.

Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China
Nanjing National Laboratory of Microstructures, The Jiangsu Provincial Key Laboratory of Advanced Photonic and ElectronicMaterials, and School of Electronic Science and Engineering, Nanjing University, Nanjing, China

References

References is not available for this document.