Growth and crystal properties of Tl-doped PbTe crystals grown by Bridgman method under Pb and Te vapor pressure

Abstract

Growth of high-quality Tl-doped p-type PbTe single crystals by Bridgman method under controlled Te or Pb vapor pressure has been investigated. For high concentration of Tl in the melt (0.65 at%), the hole concentrations for crystals grown under applied Pb vapor pressures (1.5×10 19–2×10 19 cm −3) are higher than those for crystals grown under applied Te vapor pressures (5×10 18–8×10 18 cm −3). For low concentration of Tl (0.082 at%), the hole concentration is decreased with increasing Te vapor pressure. The PbTe crystals grown with high concentration of Tl under applied Pb vapor pressures show small FWHM of X-ray rocking curve ranging from 20 to 50 arcsec. Their etch pit densities are in the range of 8×10 4–6×10 5 cm −2, which are an order of magnitude lower than those of undoped PbTe crystals. These results indicate that highly Tl-doped (0.65 at%) PbTe crystals, in particular, those grown under applied Pb vapor pressure, have an excellent crystal quality.