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Sensors 2017, 17(8), 1852; doi:10.3390/s17081852

Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics

1
College of Information Science and Technology, Dalian Maritime University, Linghai Road 1, Ganjingzi District, Dalian 116026, China
2
College of Marine Electrical Engineering, Dalian Maritime University, Linghai Road 1, Ganjingzi District, Dalian 116026, China
3
School of Optical and Electronic Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China
*
Authors to whom correspondence should be addressed.
Received: 17 June 2017 / Revised: 29 July 2017 / Accepted: 8 August 2017 / Published: 10 August 2017
(This article belongs to the Special Issue Gas Sensors based on Semiconducting Metal Oxides)
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Abstract

The density of oxygen vacancies in semiconductor gas sensors was often assumed to be identical throughout the grain in the numerical discussion of the gas-sensing mechanism of the devices. In contrast, the actual devices had grains with inhomogeneous distribution of oxygen vacancy under non-ideal conditions. This conflict between reality and discussion drove us to study the formation and migration of the oxygen defects in semiconductor grains. A model of the gradient-distributed oxygen vacancy was proposed based on the effects of cooling rate and re-annealing on semiconductive thin films. The model established the diffusion equations of oxygen vacancy according to the defect kinetics of diffusion and exclusion. We described that the steady-state and transient-state oxygen vacancy distributions, which were used to calculate the gas-sensing characteristics of the sensor resistance and response to reducing gases under two different conditions. The gradient-distributed oxygen vacancy model had the applications in simulating the sensor performances, such as the power law, the grain size effect and the effect of depletion layer width. View Full-Text
Keywords: semiconductor gas sensor; oxygen vacancy; inhomogeneous distribution; sensing mechanism; defect behavior; kinetics semiconductor gas sensor; oxygen vacancy; inhomogeneous distribution; sensing mechanism; defect behavior; kinetics
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Liu, J.; Gao, Y.; Wu, X.; Jin, G.; Zhai, Z.; Liu, H. Inhomogeneous Oxygen Vacancy Distribution in Semiconductor Gas Sensors: Formation, Migration and Determination on Gas Sensing Characteristics. Sensors 2017, 17, 1852.

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