On the application of a numerical model to improve the accuracy of the seebeck coefficient in CMOS materials

Modeling of CMOS Single Membrane Thermopile Detector Arrays

“…1 for a comparison of the real device and the numerical model). Firstly, the metal pin pads around the membrane are removed as they have negligible effect on both the electrical and thermal behaviour of the chip [15]. Secondly, as each device contains 64 identical thermopiles, only 9 pixels and the metal tracks around them are left in the 3D simulation, which significantly reduces the number of mesh elements and the computation time.…”

“…Their operation is based on the thermoelectric (Seebeck) effect, giving a voltage signal V T = N • α • ∆T proportional to a collection of thermocouples N , the Seebeck coefficient α (a thermo-electric material property) and the temperature gradient ∆T across the thermopile [12], [13]. Thermopile based FPAs are typically made of serially connected thermocouples [13], each comprising two conductors or semiconductors with different Seebeck coefficients (e.g., p + /n + doped polysilicon [11], [14], [15], and p + /n + single-crystal silicon [10], [15]). To maximise the ∆T with the incident IR radiation, the thermocouple's 'cold junctions' are normally bonded to a heatsinking substrate, whereas their 'hot junctions' are placed on a thermally isolated membrane.…”

“…Reference [14] characterizes C in a linear MEMS thermopile detector array, while reference [24] presents a three-dimensional (3D) model to simulate the temperature distribution of a 256 pixel linear array thermopile. Reference [15] implements multiphysics modelling (including joule heating, heat transfer and Seebeck effect) of four thermopiles formed by different CMOS materials to enhance the Seebeck coefficient. However, there have been very few studies focused on the numerical simulation or modelling of thermopile FPAs.…”

Crosstalk Analysis of a CMOS Single Membrane Thermopile Detector Array

“…For a comprehensive depiction of the thermopile's behaviour, we use the heat transfer module, and the electric current module of the commercial software package COMSOL Multiphysics [27]. We reduce the complexity of our model by making the following two simplifications (a comparison between the structure of the real chip and that of our model is shown in Figure 3): we remove the metal pin pads around the membrane (Figure 3a,b), considering their negligible effect on both the electrical and thermal behaviour of the chip [20]; and, we simulate only 9 pixels at the centre of the membrane, and the metal tracks surrounding them (Figure 3b), considering the device contains 64 identical thermopiles (thus reducing the computation time). The 3-dimensional (3D) view of our model (Figure 3c), shows an air cube placed on top of the chip to account for heat losses in the air.…”

“…Thermopiles are typically made of a series of thermocouples [18], each comprising two conductors (e.g., p + /n + doped polysilicon [14,19,20], or silicon [13,20]) with dissimilar Seebeck coefficients (typically ∼300 µV/K [20]), where one "hot junction" can be heated while the opposite "cold junction" is thermally bonded to a heat-sinking substrate [21]. The thermocouple generates a voltage V T = α∆T [18] when a temperature gradient ∆T is present across its junctions, where α is the Seebeck coefficient (a measure of the material's efficiency to thermally generate a voltage [17]).…”