<title>Electron velocity overshoot in GaAs studied by subpicosecond Raman spectroscopy: carrier density dependence</title>

Abstract

Electron transient transport in a GaAs-based p-i-n nanostructure under the application of an electric field has been studied by transient Raman spectroscopy at T equals 80 K. The non-equilibrium electron distribution function and electron drift velocity were measured at an applied electric field intensity of E equals 25 kV/cm and for various injected electron-hole pair densities ranging from 1017 cm-3 to 1019 cm-3. Our experimental results show that, the electron distribution is very much out of equilibrium for n is congruent to 1017 cm-3; however, as the electron-hole pair density increase the electron distribution function approaches that of the equilibrium case, in particular, as the carrier density increases to n is congruent to 1019 cm-3, electron distribution becomes very much in equilibrium and electron drift velocity becomes almost zero. These results have been explained by the effects of momentum randomization and screening of effective electron field by the injected electron-hole pairs.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.