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Proceedings Paper

Deep ultraviolet (254 nm) focal plane array
Author(s): Erdem Cicek; Zahra Vashaei; Ryan McClintock; Manijeh Razeghi
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Paper Abstract

We report the synthesis, fabrication and testing of a 320 × 256 focal plane array (FPA) of back-illuminated, solarblind, p-i-n, AlxGa1-xN-based detectors, fully realized within our research laboratory. We implemented a novel pulsed atomic layer deposition technique for the metalorganic chemical vapor deposition (MOCVD) growth of crackfree, thick, and high Al composition AlxGa1-xN layers. Following the growth, the wafer was processed into a 320 × 256 array of 25 μm × 25 μm pixels on a 30 μm pixel-pitch and surrounding mini-arrays. A diagnostic mini-array was hybridized to a silicon fan-out chip to allow the study of electrical and optical characteristics of discrete pixels of the FPA. At a reverse bias of 1 V, an average photodetector exhibited a low dark current density of 1.12×10-8 A/cm2. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower and falling off three orders of magnitude by 285 nm. After indium bump deposition and dicing, the FPA is hybridized to a matching ISC 9809 readout integrated circuit (ROIC). By developing a novel masking technology, we significantly reduced the visible response of the ROIC and thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allowed the FPA to achieve high external quantum efficiency (EQE): at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated.

Paper Details

Date Published: 16 September 2011
PDF: 9 pages
Proc. SPIE 8155, Infrared Sensors, Devices, and Applications; and Single Photon Imaging II, 81551O (16 September 2011); doi: 10.1117/12.904984
Show Author Affiliations
Erdem Cicek, Northwestern Univ. (United States)
Zahra Vashaei, Northwestern Univ. (United States)
Ryan McClintock, Northwestern Univ. (United States)
Manijeh Razeghi, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 8155:
Infrared Sensors, Devices, and Applications; and Single Photon Imaging II
Manijeh Razeghi; Paul D. LeVan; Ashok K. Sood; Priyalal S. Wijewarnasuriya, Editor(s)

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