Sensors 2017, 17(8), 1852; https://doi.org/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)
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-TextKeywords:
semiconductor gas sensor; oxygen vacancy; inhomogeneous distribution; sensing mechanism; defect behavior; kinetics
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MDPI and ACS Style
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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