Effects of Uniaxial Stress on the Electrical Resistivity and the Gunn Effect in n -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 X₁ valleys are the important valleys for electron transfer at high electric fields. The deformation potentials obtained for the X₁ valleys are Ξ_μ¹=16.8 eV/(unit strain), Ξd¹=-5.1 eV/(unit strain), and, for the $〈000〉$ or Γ₁ valley, Ξd⁰=7.8 eV/(unit strain).