Transport measurements in p-type CdTe single crystals and ion-beam doped thin films

Electrical transport properties of phosphorus-doped p-type CdTe single crystals and phosphorus-ion-beam doped, homoepitaxial thin films have been investigated by means of van der Pauw Hall effect and resistivity measurements as a function of temperature from 8 to 400 K. Analysis of the data indicates a maximum doping level greater than 2×10¹⁷ cm^-3 in the films, at least as high as in the single crystals. Phosphorus has an ionization energy of about 40 meV, the degree of compensation is smaller in the films, room temperature mobilities of the films are lower than those for single crystals by about 20%, and the temperature dependence of mobility is similar for both crystals and films. Impurity scattering is dominant at lower temperatures and polar mode scattering is dominant at higher temperatures with a maximum mobility at 150-190 K. Both the single crystals and the ion-assisted doped films show a temperature independent resistivity at temperatures below 40 K, indicating the presence of impurity band conduction.