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Optical Engineering

Figures of merit and optimization of a VO2 microbolometer with strong electrothermal feedback
Author(s): G. Neto; Luiz Alberto Luz de Almeida; Antonio Marcus Nogueira-Lima; C. S. Moreira; H. Neff; Igor A. Khrebtov; Valery G. Malyarov
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Paper Abstract

The influence of electrothermal feedback and hysteresis on the operation conditions, noise, and performance of a VO2 transition-edge microbolometer has been evaluated. The material undergoes a first-order semiconductor-to-metal phase transition (SMT) within the temperature range 40<T<70 °C. Due to electrothermal feedback, all device parameters, including the required heat-sink temperature, output voltage and current response, response time, linear dynamic range, responsivity, noise, and detectivity, display complex and nonlinear variations with temperature, electrical biasing conditions, input radiation levels, and hysteresis width. In the constant-current mode, the device responsivity extends over a broad temperature range, but under constant-voltage operation it is sharply localized and restricted to the SMT center. Film quality, as represented by the transition and the hysteresis width and the flicker noise magnitude, crucially affects device performance. In the weak hysteretic case and at low 1/f noise levels, the device detectivity improves substantially in both operation modes. The spectral range of the device is largely determined by the optical absorptivity of the VO2 film. For operation within the SMT, it extends well into the far IR wavelength region of the atmospheric window, but is substantially smaller for operation in the semiconducting region.

Paper Details

Date Published: 1 July 2008
PDF: 15 pages
Opt. Eng. 47(7) 073603 doi: 10.1117/1.2956386
Published in: Optical Engineering Volume 47, Issue 7
Show Author Affiliations
G. Neto, Univ. Federal da Bahia (Brazil)
Luiz Alberto Luz de Almeida, Univ. Federal da Bahia (Brazil)
Antonio Marcus Nogueira-Lima, Univ. Federal de Campina Grande (Brazil)
C. S. Moreira, Univ. Federal de Campina Grande (Brazil)
H. Neff, Univ. Federal de Campina Grande (Brazil)
Igor A. Khrebtov, S.I. Vavilov State Optical Institute (Russian Federation)
Valery G. Malyarov, S.I. Vavilov State Optical Institute (Russian Federation)

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