High-field autosolitons in an electron-hole plasma in p-Ge

The formation of high-field thermodiffusion autosolitons was studied experimentally in a photogenerated electron-hole plasma heated up by an electric field in p-Ge samples oriented along the 〈111〉 axis at T=77 K. Measurements of the current-voltage characteristics, electric field distributions along the samples, and IR emission in the wavelength range λ=1.65–10 μm showed that the arising of an autosoliton was accompanied by the appearance of N-shaped current-voltage characteristic regions. Autosolitons were formed at electron-hole plasma concentrations n≥1×1014 cm−3 and field strengths E≥500 V/cm. They manifested themselves as static, moving, and pulsating strata with field strengths Eas=1000–20000 V/cm and carrier temperatures Te≥1000 K. We also observed a turbulent electron-hole plasma state when autosolitons chaotically appeared and disappeared in the samples. The multivalley band structure of germanium influenced the dynamics of autosoliton formation; intervalley transfer of electrons in the strong field of autosolitons caused a three-step autosoliton field growth.