Abstract:
An analytical model is proposed to describe the spatial resolution of 2D IR photodiode arrays with a diode-size value close to the pixel size. The model allows one to analyze the important case of diode arrays with small pixel sizes and an arbitrary ratio of the latter to the diffusion length of charge carriers and to the absorber-layer thickness. In addition to the usual Sinc-multiplier, the expression for the modulation transfer function of the analyzed diode arrays includes a factor that describes the deviation from the Sinc-multiplier, this deviation increasing with spatial frequency. The effect due to the additional factor becomes more appreciable with decreasing the array pitch and/or with increasing the photosensitive-layer thickness. A quantitative comparison of calculations within the proposed model with calculations using the Monte Carlo method for modeling the diffusion of photogenerated charge carriers is performed.
Keywords:analytical model, 2D IR detector, spatial resolution, nyquist frequency, line spread function, modulation transfer function.
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