PbTe EPITAXIAL LAYERS GROWTH BY THE HOT WALL TECHNIQUE

Abstract

The Hot Wall Epitaxy (HWE) technique can be defined as an evaporation process in which the main characteristic is the growth of epitaxial layers under conditions as near as possible to the thermodynamic equilibrium, with a minimum loss of material. The process differs from a normal evaporation method by the use of a heated collimator whose function is to confine and direct the vapor from the source to the substrate. In this way it is possible to avoid loss of material, to keep the vapor pressure high and to reduce to a minimum the temperature difference between source and substrate. In the PbTe samples grown in this work, the carrier concentration varied from 7 x 10 16 to 5 x 10 18 cm -3 for p- and n-type layers. The highest mobility at 77 K was 3.14 x 10 4 cm 2 /V.s. but values from 2.1 x 10 4 to 2.8 x 10 4 cm 2 /V.s were obtained very often for n-type layers. The highest mobility for p-type was 1.2 x 10 4 cm 2 /V.s. The best mobility for n-type layers reached the value of 8 x 10 5 cm 2 /V.s at 12 K.