Space-Charge Scattering and Electron Transport in n GaAs

Abstract

The effect of the space‐charge scattering mechanism on the Seebeck coefficient of n GaAs was examined in the temperature range 4–300 K. The measured Seebeck coefficient was combined with the Hall coefficient and conductivity to determine the dominant electron scattering mechanism from 100 to 300 K. Impurity‐band conduction dominated at lower temperatures. The measurements were performed on highly compensated samples with electron carrier concentrations in the range 10¹⁵−10¹⁸ cm⁻³. The measured transport properties are compared to theoretical predictions based on polar, ionized impurity, and space‐charge scattering mechanisms. Satisfactory agreement with theory is obtained if the space‐charge mechanism is included in the Seebeck coefficient as well as in mobility calculations. The experimental results indicate that the space‐charge mechanism can dominate at room temperature and below for highly compensated n GaAs.