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The carrier lifetimes in In x Ga 1-x As (InGaAs) and Hg 1-x Cd x Te (HgCdTe) ternary alloys for radiative and Auger recombination are calculated for temperature 300K in the short wavelength range 1.5 < λ < 3.7 µm. Due to photon recycling, an order of magnitude enhancements in the radiative lifetimes over those obtained from the standard van Roosbroeck and Shockley expression, has been assumed. The possible Auger recombination mechanisms (CHCC, CHLH, and CHSH processes) in direct-gap semiconductors are investigated. In both n-type ternary alloys, the carrier lifetimes are similar, and competition between radiative and CHCC processes take place. In p-type materials, the carrier lifetimes are also comparable, however the most effective channels of Auger mechanism are: CHSH process in InGaAs, and CHLH process in HgCdTe. Next, the performance of heterostructure p-on-n photovoltaic devices are considered. Theoretically predicted R o A values are compared with experimental data reported by other authors. In 0.53 Ga 0.47 As photodiodes have shown the device performance within a factor of ten of theoretical limit. However, the performance of InGaAs photodiodes decreases rapidly at intermediate wavelengths due to mismatch-induced defects. HgCdTe photodiodes maintain high performance close to the ultimate limit over a wider range of wavelengths. In this context technology of HgCdTe is considerably advanced since the same lattice parameter of this alloy is the same over wide composition range.

The theoretical performance of medium wavelength infrared (MWIR) InAsSb-based ternary alloy photodiodes is examined theoretically taking into account thermal generation governed by the Auger and radiative mechanisms. The contribution of spin-off band on carrier lifetime in p-type InAsSb ternary is re-examined due to new insight into composition dependence of spin-orbit-splitting band gap energy. The investigations are carried out for photodiodes operated at room temperature. The effects of doping profiles on the photodiode parameters (R 0 A product and detectivity) are considered. The theoretical predictions of photodiode parameters are compared with experimental data published in the literature.

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The performance of long-wavelength n+-on-p and p-on-n HgCdTe photodiodes is reexamined theoretically. It is assumed that the performance of photodiodes is due to thermal generation governed by the Auger mechanism. The influence of junction position on the R0A product, photoelectrical gain, and noise for both types of HgCdTe photodiodes operated at 77 K, with 0.1 eV base material, is considered. Especially, the R0A product as a function of cutoff wavelength and temperatures is analyzed in detail for both type of structures. For assumed doping concentrations in the base region of homojunctions (Na=5×1015 cm−3 for the n+-on-p structure and Nd=5×1014 cm−3 for the p-on-n structure), the influence of a p-type cap layer on the effective R0A product is more serious for p-on-n structures in comparison with influence of an n+-type layer on the R0A product for n+-on-p junctions. Therefore, to suppress the deleterious influence of cap layers (especially in the case of p-on-n junctions), a wider band-gap cap layer is necessary. For a given cutoff wavelength, the theoretical values of the R0A product for p-on-n photodiodes in the temperature range below 77 K are a little greater than for n+-on-p photodiodes, which is due to lower doping. In the higher temperature range for very long-wavelength photodiodes, p-type base devices are more advantageous. Results of calculations are compared with experimental data reported by other authors.