Ionized Impurity Density in n-Type GaAs

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Abstract
Total ionized impurity densities (ND+NA) from 7×1013 to 3×1017 cm−3 are determined for epitaxial samples of n‐type GaAs by analyzing mobility and carrier concentration data as a function of temperature with the Brooks‐Herring formula for ionized impurity scattering. This procedure results in the determination of a temperature range within which the effects of other scattering mechanisms are minimal and gives values of ND and NA which are in good agreement with impurity densities obtained from analyses of the temperature variation of the Hall constant. These results are then used to determine empirical curves relating the impurity density to the 77°K Hall mobility. With these data a good estimate of the total ionized impurity concentration in a sample can be determined from Hall constant and resistivity measurements at 77°K.