Metal/Porous Silicon Schottky Diode Structures as Sensors
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0915-R06-13
Metal/Porous Silicon Schottky Diode Structures as Sensors Tayyar Dzhafarov1,2, Cigdem Oruc Lus1, Sureyya AYDIN1, and Emel Cingi1 1 Physics, Yildiz Technical University, Davutpasa, Istanbul, 34210, Turkey 2 Institute of Physics, Azerbaijan National Academy of Sciences, Javid str., Baku, Azerbaijan, AZ-1143, Azerbaijan ABSTRACT In this work we present data on investigation of the current-voltage and capacitance characteristics of Au/PS Schottky type structures in the presence of different hydrogencontaining solutions (sodium borohydride, sodium tetraborate pentahydrate, glucose, ethanol, methanol, boric acid, , benzine, KOH). Generation of the open-circuit voltage and short-circuit current density and capacitance up to 0.55 V, 25 mA/cm2 and 1µF respectively on placing of Au/PS structures in these solutions was discovered. This effect is mainly caused by hydrogen component of solutions. The possible mechanism generation of voltage and capacitance in metal/PS sensors hydrogen-containing solutions is suggested. The advantage of metal/PS Schottky type sensors consists in working without applying external electricity. INTRODUCTION Interest to porous silicon (PS) materials is very intesive in the recent years due its potential applications, as humidity and gas sensors, in various areas such as air-quality monitoring, fuel cell, biomedical sciences and chemical industries [1]. The large surface to volume ratio (about of 500m2/cm3) and high surface reactivity due to the presence the silicon hydrides and silicon oxides, give it the capability to react with gases and sense them readily [2]. Gas-stimulated change of electrical properties, such as resistance [3] or capacitance [4] of PS, is the sensing parameters of PS-based sensors. The mechanism of gas-induced sensitivity are generally associated with a change in the carrier concentration in the PS, due to the adsorbed molecules or change in dielectric constant, as a result of gas penetration inside the pores. Changes of electrical resistance of PS layers in the presence of inorganic gases and organic vapors (ethanol, methanol, acetone and LPG) have been observed [5,6]. It is obviously that work of such resistive or capacitive type sensors demands to apply of electricity from external source. The operation of new type humid and gas sensors on base of metal/PS Schottky-type structures have been investigated in [7-9]. The operation of metal/PS type gas sensors does not demand applying of electricity. On the contrary, such structures produce electricity in humid and gas ambient. Data on changes of current-voltage characteristics and capacitance of metal/PS Schottky-type structures on dipping in different hydrogen-containing solutions (glucose, ethanol, methanol, boric acid, sodium tetraborate pentahydrate, sodium borohydride, benzine, KOH) were presented in this paper. In this paper we present data on changes of current-voltage characteristics and capacitance of metal/PS Schottky-type structures on dipping in different hydrogen-containing solutions (sodium borohydride
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