Negative diffusion capacitance in auger-Suppressed HgCdTe heterostructure diodes
Abstract
An ac analytical model of the diffusion capacitance properties of a pπn HgCdTe heterostructure extracting diode is developed. The results show that the diffusion capacitance dominates the impedance, and can be negative, depending on the length of the intrinsic region. Experimental results on typical diodes show a capacitance of the magnitude predicted, but with a rather more complex frequency dependence, with two changes in sign in the frequency range 20 Hz-1 MHz. The existence of a negative capacitance region is not found to be dependent on the existence of a negative resistance region. The discrepancy between theory and experiment is ascribed to the existence of charge trapping. The results are also discussed in terms of time domain variation of a small perturbation current. The results for the capacitance at high frequency are used to predict the high frequency performance limit of such devices.
- Publication:
-
Journal of Electronic Materials
- Pub Date:
- August 1996
- DOI:
- 10.1007/BF02655001
- Bibcode:
- 1996JEMat..25.1151P
- Keywords:
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- Cadmium mercury telluride;
- diffusion capacitance;
- heterostructure diode