PN Nanojunctions in Compound Semiconductors
Technical Report,01 Sep 2011,31 May 2018
University of Rochester Rochester United States
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Overall Goal Understanding and Suppression of Dark Current in MWIR Detectors This was a fairly long program after a few renewals, it last just short of 7 years from Sept. 1, 2011 to May 31, 2018. The specific goals individually discussed below evolved over the duration of the program, but there was a constant central goal understanding and suppression of dark current in mid-wave infrared MWIR, 3-5 um detectors. Significance of the Problem of MWIR Detector Dark Current Dark current and its noise-creating fluctuations are the major limitations of MWIR detector performance. MWIR detectors dark current at room temperature is at least a million times greater, and often even quite a bit more than that, in comparison to SWIR telecom detectors. Thus dark current reduction is important aspect of MWIR detector research. Approach The problem of reducing dark currents is complicated by the fact that there are many different physical mechanisms that can produce dark current, and the dominant mechanism varies from detector to detector. Large device vs. small MWIR vs. LWIR superlattice vs. bulk material room temperature vs. cooled. All these factors influence which dark current mechanism is the dominant one. A particular approach for reducing one type of dark current will usually be completely ineffective in reducing a different type of dark current. The is a need, addressed by this proposal, for comprehensive method to determine the dominant dark current mechanism and design devices to suppress it. Step 1. Identify the Dark Current Mechanism Our first step toward reducing dark current is identifying the physical mechanism that produces the dark current. At the beginning of this program, bulk dark current mechanisms in MWIR detectors were widely understood by the IR detector community, but surface current was poorly understood. A major goal of the present program was surface dark current understanding its mechanisms and developing approaches to suppress it.
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