Influence of electrical characteristics on the sensitivity of p-InP-based pseudo-Schottky diodes for NO sub(2) monitoring in atmosphere

This article is devoted to the optimization of the electrical parameters of p-InP-based Schottky diodes realized with gold metal, in order to enhance their NO sub(2) gas sensitivity. In the structures based on p-InP, the interface states that exist at the surface of the semiconductor are responsible...

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Bibliographic Details
Published in:Sensors and actuators. B, Chemical Chemical, 2008-09, Vol.134 (2), p.597-603
Main Authors: Varenne, C, Brunet, J, Pauly, A, Lauron, B
Format: Article
Language:English
Subjects:
Barriers
Electrical junctions
Fermi level
Fermi surfaces
Gas sensors
Nitrogen dioxide
Pinning
Semiconductors
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Summary:This article is devoted to the optimization of the electrical parameters of p-InP-based Schottky diodes realized with gold metal, in order to enhance their NO sub(2) gas sensitivity. In the structures based on p-InP, the interface states that exist at the surface of the semiconductor are responsible for the undesirable Fermi level pinning, and the value of the Schottky barrier height ( sub(B)) thus becomes limited by this phenomenon. In gas sensor application, the sensitivity varies as the Schottky barrier height varies. Therefore, to reduce the effect of the Fermi level pinning, one solution is to realize a pseudo-Schottky junction: a thin opposite doping layer to that of the bulk is created between the metal and the p-InP. This can be realized by introducing a germanium (Ge) layer during the evaporation of the metal, followed by an annealing process. The mechanisms of the electrical conduction of these structures are analyzed at different temperatures. The influence of the electrical properties, namely barrier height ( sub(B)) and n (ideality factor) on these devices sensitivities towards NO sub(2) are demonstrated. Through the values of the ideality factor, we investigate its influence on the conduction mechanism and on the sensitivity of the gas sensor.
ISSN:0925-4005
DOI:10.1016/j.snb.2008.06.002