| Autor: |
G.L. Deste´fanis, R. Roussille, R. Boch |
| Rok vydání: |
1982 |
| Předmět: |
|
| Zdroj: |
Journal of Crystal Growth. 59:270-275 |
| ISSN: |
0022-0248 |
| DOI: |
10.1016/0022-0248(82)90335-9 |
| Popis: |
It is well known today that damage induced by ion implantation in Hg1−xCdxTe is responsible for the n+ electrical activity obtained without annealing and that the formation of this layer depends little on the conditions of implantation and on the characteristics of the material used. Nevertheless the mechanism responsible for the formation of the n+ layer is unknown. The aim of this work is to report some new results on ion implantation in thin epilayers (of Hg1−xCdxTe on CdTe) which could contribute to the understanding of this phenomenon. We have found that although defects are the cause of electrical activity, there is no good correlation between the density of defects (as observed by channeling experiment) and the density of carriers (measured by Hall effect or infrared reflectivity). For boron implantations we observe saturation both in carrier concentration (2×1018 cm-3) and in defect concentration (15%). Nevertheless saturations occurs for very different doses (1013 cm-2 for doping, 1015 cm-2 for defects). Before reaching the carrier concentration of 2×1018 cm-3, the material becomes degenerate, the Fermi level climbs into the conduction band and a large Moss-Burstein shift is expected. We have observed such a shift by infrared spectrophotometry and found that it is closely correlated with the electrical doping. Calculations of degeneracy are in good agreement with optical measurements. When the saturation of carrier concentration is reached the apparent gap becomes constant and the Fermi level seems to be pinned in the conduction band. This pinning effect could be attributed to a large peak in the density of states induced by defects and could explain why saturation in doping and in damage is not reached for the same doses. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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