Heteroepitaxial PbTe-on-Si pn-junction IR-sensors: correlations between material and device properties
✍ Scribed by Dmitri Zimin; Karim Alchalabi; Hans Zogg
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 86 KB
- Volume
- 13
- Category
- Article
- ISSN
- 1386-9477
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✦ Synopsis
Epitaxial IV-VI narrow band gap semiconductors on Si(1 1 1) substrates exhibit high structural quality despite the large lattice and thermal expansion mismatch. Test arrays with photovoltaic n + -p PbTe infrared sensors (cut-o wavelength 5:5 m at 80 K) of di erent sizes were fabricated and analyzed. The sensitivities are generation-recombination (g-r)-limited in the 90 -200 K range. The g-r carrier lifetimes in the depletion region are determined from the R0A-products (inverse noise current densities). The corresponding carrier di usion lengths are correlated with the material properties, namely low-temperature saturation Hall mobilities and X-ray rocking curve line widths. It turns out that all these parameters are determined by the density of the threading dislocations, and each dislocation crossing the active area gives rise to a shunt resistance. At lower temperatures, the R0A-products saturate and the ideality factors increase above a value of 2. This behaviour suggests that, as in the case of Schottky barriers of metal-semiconductor junctions of IV-VIs, uctuations of the built-in electric ÿeld occur near the dislocation cores which cross the active areas of the devices.