Vitreous Chalcogenide Semiconductors for Gas Sensing Application
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A5.8.1
Vitreous Chalcogenide Semiconductors for Gas Sensing Application 1
Serghei V. Dmitriev, 2Igor V. Dementiev 1 Department of Industrial and Environmental Chemistry, Moldova State University 2 Department of Physics, Moldova State University 60, A.Mateevici Str., Chisinau, MD-2009, Moldova
ABSTRACT
Report presents results of research aimed the investigation of possibility to use such chalcogenide materials as vitreous As2S3, As2Se3 and their solid solutions for gas sensors applications. For a long time these materials were well-known as materials mostly used for optical information registration. Developed approach allows to widening the sphere of application of given materials and create new class of gas sensitive devices. Thin film gas sensitive elements on the base of solid solutions of (As2S3)x-(As2Se3)1-x (where x=0; 0.3; 0.5; 0.7 and 1.0) were obtained by means of the thermal evaporation under vacuum conditions 10-5 Torr. Thin films can be deposited on both hard and flexible substrate. Formed films had specific resistance on the level 1010-1014 Ohm.cm (on dependence on composition) at the thickness of 1-2 µm. It was established that CGS thin films possess gas sensitivity S, determined as S=(GgasGait)/Gair, on the level 2-3 relative units for CO and 7-8 for hydrogen at the 100 ppm concentration levels of both gases in atmosphere already at the room temperature that allows to excluding the heater from the gas sensor construction decreasing through that both manufacturing and operational cost. It is concluded that chalcogenide semiconductor materials can be considered as perspective materials for gas sensor application, including space exploration application.
INTRODUCTION
For the control of the state of surrounding atmosphere currently there are commonly used relatively simple solid-state metal oxide based resistive sensors [1-3]. At the same time many research efforts aiming to develop innovative environmental monitoring systems for the early detection and measuring of concentrations of toxic and inflammable gases have been undertaken to substitute the standard analytical tools with a new generation of portable devices [4-6] and so the search of new materials and technologies for gas sensors manufacturing is continuing. Some of such new materials, which could be used for gas sensing application, are being vitreous chalcogenide semiconductors (VCS). The first attempts to use chalcogenide materials (ternary solid solutions of As-S-Te system) for gas sensors creation were undertaken by D.Tsiulyanu et al. [7,8]. The chalcogenide glasses are one of the most widely known families of amorphous materials and have been extensively studied for several decades because of their interesting fundamental properties and their potential applications in optical imaging, optical recording and integrated optics, microelectronics and optical communications [9-11].
A5.8.2
Giving general characteristics to these materials we can state the next. Chalcogenide glasses are based on such chalcogen chemical elements as Se, S and
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