An analytic model employing an elliptical surface area to determine the gaseous thermal conductance of uncooled VOx microbolometers

Abstract

This work presents a detailed overview of the analytic methods for calculating the beam and gaseous thermal conductance components associated with uncooled VO x microbolometers. The conventional method to calculate the gaseous component relies on the assumption that the entire plate is maintained at a uniform temperature, thus the surface area of the plate is used for the calculation. We have observed using an industry leading multiphysics simulator that this assumption is not strictly true for VO x microbolometers as the conduction pattern exhibits an elliptical shape. Based on this, we have developed and propose an analytic method that employs an elliptical surface area scaled appropriately with the device dimensions to obtain an estimate of the average temperature conduction pattern. Prototype devices were manufactured and experimentally characterised. The devices exhibit thermal conduction characteristics comparable to those in literature and industry, and we could achieve 0.5 µW/K under vacuum conditions and 15 µW/K at atmospheric pressure with a TCR of −1 %/K. However, both simulated and experimental result sets of the gaseous thermal conductance exhibit large deviations from the conventional analytic method, on average approximately 40 %. The proposed method reduces this average error significantly to less than 10 % when compared to the simulated results.

Dual‐Crossbar Configurated Bi2O2Se Device for Multiple Optoelectronic Applications

“…Besides, it is noticed that the photoresponse of the TSH device for the case of Bi 2 O 2 Se shows bolometric-induced non-volatile characteristics, while presenting a volatile feature in the MoS 2 case. We collected the thermal conductivity of various 2D materials and substrates (see Table S3, Supporting Information), finding that the thermal conductivity of Bi 2 O 2 Se (1.94 W/m•K) [56] is extremely small, nearly two orders of magnitude lower than that of MoS 2 (76.2 W/m•K) , [57] and even much lower than those of the conventional bolometer materials VO x [58] and amorphous Si . [59] Comsol simulation results present the temperature field distribution of the Bi 2 O Se/SiO 2 device and MoS 2 /SiO 2 device under Gaussian beam irradiation, no detectable temperature vibration can be found along the vertical direction of MoS 2 , while the temperature gradient in the cross-section of Bi 2 O 2 Se is apparent (See Figure 4j).…”

A two-port electrothermal model for suspended MEMS device structures with multiple inputs

“…These applications have penetrated the industrial, military, and consumer markets, showing their diversity and the extensive marketing opportunities they present. Examples include the likes of on-chip sensors for diagnostics (Sisto et al, 2010;Zhang et al, 2009), chemical detection (Corsi et al, 2012;Barritault et al, 2013), thermal conductivity sensors (heat flow sensors and micro-hotplates) (Senesac et al, 2009;Arndt, 2002;Elmi et al, 2008), air flow sensors (Baltes et al, 1998;Johnson and Higashi, 1987;Simon et al, 2001), and thermal imaging microbolometers (Akula et al, 2011;Dulski et al, 2013;Castaldo et al, 1996;Liddiard, 2013).…”