InP-based multilayer structures are largely applied in fabrication of heterojunction transistors and optoelectronic devices. Recently, our experimental and theoretical studies of InP epitaxial layer behaviour in gas atmosphere showed the large sensitivity of the layer resistance and surface Fermi level position to adsorption of ionic species and, on the other hand, marked stability of the initial resistance in pure air versus time [1, 2]. These properties allowed the construction of a novel high-sensitivity InP based gas sensor for toxic gas detection working in the ppb range [1]. The growing interest in such kind of sensing structures, easily integrated with other III-V devices, requires further optimisation of their parameters. In this order, systematic research of sensor electronic and chemical properties, in particular focused on a surface and near-surface region are necessary.

In this paper, the resistance response of gas sensing n-InP epitaxial layer based structures was examined under oxidising gas (NO₂) exposition, at temperature of 80 and 100⁰ C. The gas concentration varied in a very low range from 20 to 100 ppb. The stabilization of the layer initial resistance and evolution of sensor response due to cycles of adsorbed gases was systematically investigated. The experiments were carried out for different thickness of InP layers (in the submicron range) to reveal the influence of the depletion layer on the gas sensitivity. The experimental data were compared with the results of numerical analysis of the influence of surface states and near-surface region on the relative resistance changes upon ion adsorption. In addition, the spectroscopic studies, using XPS technique, of the chemical properties of InP surfaces before and after gas submission were performed.

[1] L. Talazac et al., Sensors and Actuators B 76 (2001) 258

[2] B. Adamowicz et al., Thin Solid Films 436 (2003) 101

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/3726 must be provided.

1. Theoretical analysis of oxygen adsorption at SnO₂ grains with slab geometry
2. A theoretical analysis of the electronic properties of tin dioxide surface
3. Rigorous analysis of the contribution of surface states to the conductivity of semiconductor thin layers