Low-temperature franz-keldysh oscillations in uniaxially stressed germanium

In this paper we report some typical results of high-field electroreflectance on single crystals of germanium, stressed uniaxially along the (001) direction. Measurements were made at 10°K near the fundamental direct edge. The electric field was applied by Schottky barrier. Franz-Keldysh oscillations exhibiting up to twenty peaks enabled us to determine the broadening parameter Γ = 1.4 meV and the ratio of the reduced masses μ₀₂/μ₀₁ = 0.97.