Physics-based simulation of the modulation transfer function in HgCdTe infrared detector arrays

Abstract

We have developed a numerical technique for performing physics-based simulations of the modulation transfer function (MTF) of infrared detector focal plane arrays. The finite-difference time-domain and finite element methods are employed to determine the electromagnetic and electrical response, respectively. We show how the total MTF can be decomposed to analyze the effect of lateral diffusion of charge carriers and present several methods for mitigation of such effects. We employ our numerical technique to analyze the MTF of a HgCdTe two-color bias-selectable infrared detector array.

Three-dimensional numerical simulation of planar P+n heterojunction In0.53Ga0.47As photodiodes in dense arrays part II: modulation transfer function modeling

“…Taking the current response to coherent illumination as the device optical impulse response, then we estimate the impulse response by dividing out the frequency domain spatial averaging contributions from the finite beam dimensions. As argued in prior works, 9 the frequency domain ratio of the current response, to the optical generation ratio, provides a measure of optical and lateral carrier diffusion crosstalk.…”

“…The methodology for eliciting representative modulation transfer functions by numerical simulation has been described for two-color and novel photon trapping HgCdTe IR detectors, 9,10 and we briefly review the details as applied here to dense P + n InGaAs on InP DLPH photodiode arrays. First, we determine the dark current in the subject pixel diode.…”

“…Following Boreman we call this averaging due to finite pixel dimensions a "footprint" (FP) MTF. [7][8][9] The finite dimension Gaussian beam also introduces a known spatial averaging, shown in the dashed green line. (GB) The dashed orange line shows the spatial averaging attributable to the sampling interval (SAMP) or inter-sample spot center spacing.…”

“…While numerically integrating the area under various response curves can provide a quantitative measure of crosstalk, 9 the figures themselves provide useful qualitative descriptions of the device operation, much like the MTF response curve indicates image quality as overall modulation transfer from object to image. 7 The difference between the photocurrent impulse response, and the optical generation curve, indicates the importance of lateral crosstalk (carrier diffusion) in reducing the system response or contrast with spatial frequency.…”

Modeling and Characterization of MTF and Spectral Response at Small Pitch on Mercury Cadmium Telluride

“…This method is currently used for MTF and spectral response computations. [11][12][13] Two equations have to be solved: an optical equation and a semiconductor equation. With the optical equation, the photogeneration is computed.…”