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

Growth of high-quality T1-doped p-type PbTe single crystals by Bridgman met hod under controlled Te or ph vapor pressure has been investigated. For hig h concentration of T1 in the melt (0.65 at%), the hole concentrations for c rystals grown under applied Pb vapor pressures (1.5 x 10(19)-2 x 10(19)cm(- 3)) are higher than those for crystals grown under applied Te vapor pressur es (5 x 10(18)-8 x 10(18)cm(-3)). For low concentration of T1 (0.082 at%), the hole concentration is decreased with increasing Te vapor pressure. The PbTe crystals grown with high concentration of T1 under applied Pb vapor pr essures show small FWHM of X-ray rocking curve ranging from 20 to 50 arcsec , Their etch pit densities are in the range of 8 x 10(4)-6 x 10(5) cm(-2), which are an order of magnitude lower than those of undoped PbTe crystals. These results indicate that highly T1-doped (0.65 at%) PbTe crystals, in pa rticular, those grown under applied ph vapor pressure, have an excellent cr ystal quality. (C) 2001 Elsevier Science B.V, All rights reserved.