Effects of Uniaxial Stress on the Electrical Resistivity and the Gunn Effect inn-Type GaAs

Electrical resistivity and Gunn-effect threshold measurements as a function of uniaxial stress were made on horizontal boat-grown GaAs and liquid epitaxial GaAs. The electron concentration of the boat-grown material exhibited an exponential change with both temperature and stress. The exponential behavior is characteristic of a semiconductor in which the electrical properties are dominated by deep trap levels. The electron concentration of the epitaxial GaAs remained nearly constant with both temperature and stress. For $〈100〉$ stresses greater than 9 kbar, the resistivity increased rapidly and the current oscillations at high electric fields were quenched. However, the resistivity and current oscillations remained nearly constant when large $〈111〉$ stresses were applied. Thus, the $〈100〉$ or $X_1$ valleys are the important valleys for electron transfer at high electric fields. The deformation potentials obtained for the $X_1$ valleys are ${{\Xi }_{\mu }}^1=16.8\mathrm{}$ eV/(unit strain), ${{\Xi }_d}^1=-5.1\mathrm{}$ eV/(unit strain), and, for the $〈000〉$ or ${\Gamma }_1$ valley, ${{\Xi }_d}^0=7.8\mathrm{}$ eV/(unit strain).