Effect of tin doping on InSb thin films

• Published in: Thin solid films 1989-05, Vol.172 (1), p.71-80
• Main Authors: Oszwałdowski, M., Berus, T.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Electronic transport in condensed matter; Exact sciences and technology; Low-field transport and mobility; piezoresistance; Physics
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/0040-6090(89)90119-3

The behaviour of tin in InSb thin films is investigated. Tin is introduced to flash-evaporated InSb films by coevaporation of tin and InSb from separate evaporation sources. Subsequently the films are regrown by hot-wire zone melting. The morphology and chemical composition of the doped films are studied by means of scanning electron microscopy and by electron microprobe and conventional X-ray analysis. The effect of doping is also studied by Hall effect measurements. It is found that to the solubility limit of tin in InSb correspond tin and electron concentrations of (1.5±0.5) × 10 20 cm -3 and (3±1) × 10 18 cm -3 respectively. Below the solubility limit the electron concentration is only a small fraction (several per cent) of the tin concentration. In spite of the large tin content the electron mobilities in the regrown films are very high; they correspond roughly to the theoretical values calculated for uncompensated n-InSb. This high mobility is explained by the assumption that most of the tin atoms incorporate in the InSb in the form of electrically inactive Sn-Sn pairs by the substitution for the isoelectronic In-Sb pairs. It appears that tin is a very useful donor dopant for obtaining high electron mobility InSb films with electron concentrations up to 2 × 10 18 cm -3. In comparison with the group VI elements tin as a dopant to InSb thin films has several advantages, discussed in the text.