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.

On the role of space-charge scattering in epitaxial GaAs

“…Before reaching the final conclusions we should like to call attention to some other indications of the importance of space-charge scattering in GaAs. One of them is derived from the analysis of thermoelectric power measurements on n-type GaAs by Hamerly and Heller [24], and the other one is derived from the results of a similar analysis of the magnetoresistance measurements by one of the present authors [25]. The thermoelectric power measurements [24] show that space-charge scattering can dominate the electron transport in GaAs a t room temperature and below.…”

“…One of them is derived from the analysis of thermoelectric power measurements on n-type GaAs by Hamerly and Heller [24], and the other one is derived from the results of a similar analysis of the magnetoresistance measurements by one of the present authors [25]. The thermoelectric power measurements [24] show that space-charge scattering can dominate the electron transport in GaAs a t room temperature and below. A similar conclusion is reached at from the analysis of magnetoresistance measurements, using the concept of "effective" relaxation time, describing the combined effects of different scattering mechanisms [25].…”

Hall Effect, Schottky Barrier Capacitance, and Photoluminescence Spectra Measurements for GaAs Epitaxial Layer and Their Correlation

“…Correlation among the experimental results, compensation ratio, and space charge scattering.--Figure 12 shows the relation between the compensation ratio and the value of the product of the space charge region density and their scattering cross section listed in Table II for samples belonging to groups A and B. It is obvious that the value of NsQ increases with the compensation ratio (23). Correlation between the sources of compensating impurities and the space charge region has been discussed by Ikoma (2, 3) regarding heattreated GaAs samples.…”