527 MODELING AND SIMULATION OF HgCdTe BASED PHOTODETECTOR FOR N 2 O GaS DETECTION 1 T. K. Parashar, 2 R. K. Lal 1 University Polytechnic, 2 Department of Electronics and Communication Engineering Birla Institute of Technology, MESRA, Ranchi. parashar303017@rediffmail.com Received 3/09/2011, online 16/09/2011 Abstract In this work an analytical modeling of p+-Hg 0.81 Cd 0.19 Te/n0-Hg 0.81 Cd 0.19 Te/CdZnTe, homojunction photodetector has been analyzed theoretically at 77K. A generic model of HgCdTe based photovoltaic detector has been developed using the closed form equations. Device parameters are obtained of the proposed photodetector and studied in terms of dark current, resistance area-product, quantum efficiency and detectivity. Study reveal that at suitable biasing conditions, the photodetector exhibits a high detectivity (2.6×10 9 mHz 1/2 /W) and suitable efficiency lies in wavelength range 15.5-19 μm with its peak at 17 μm. Proposed photodetector is best suited for N 2 O gas detection whose characteristic wavelength is 17 μm. Key words: Photodetector; Gas; Modeling. I INTRODUCTION The ternary alloy Hg 1-x Cd x Te has become an important candidate for optoelectronic devices and optical gas sensor applications due to its broad band-gap range, better stability and has a weak dependence of the energy gap bandwidth on composition. No single known material surpasses MCT in fundamental performance and flexibility. Photovoltaic detectors fabricated from HgCdTe offer fast response times, higher sensitivity and/or higher operating temperatures over other infrared detectors [1-2].Over the past few years, there has been tremendous progress in the development of HgCdTe based infrared photovoltaic detectors due to growing demand for both civilian (earth observation, environment sensing and monitoring) and military (target discrimination and identification, background clutter rejection) applications [3–4]. Mercury Cadmium Telluride (MCT) detectors have been the most important semiconductor for mid to very long-wavelength (3- 30 ȝm) infrared photodetectors. One major of utilization of these detector are in gas sensors in infrared region. A number of pollutant combustible/toxic gases and liquids such as hydrocarbons, Ammonia, Sulfur Dioxide, Nitrogen Dioxide, Nitric Oxide, Carbon Monoxide, Hydrogen Sulfide, Hydrogen Cyanide, Hydrogen Chloride, Chlorine, Arsine, Chlorine Dioxide, Fluorine, Hydrogen, Hydrogen Fluoride etc. having their characteristic absorption band located in the infrared region [5-6]. One basic drawback of these HgCdTe based devices are that they need to be operated in 77K temperature. But in compared to the ease of developed processing technology and remarkable performance obtained, it can be ignored. Here in this paper we have utilised the feature of HgCdTe based detector for the detection of N 2 O gas. In present paper, an analytical model has been developed as generally used by many researchers Journal of Electron Devices, Vol. 11, 2011, pp. 527-537 © JED [ISSN: 1682 -3427 ]