Field-induced transient hole transport in an Al_0.3Ga_0.7As-based p-i-n nanostructure studied by picosecond Raman spectroscopy

Electric field-induced transient hole transport in an Al_0.3Ga_0.7As-based p-i-n nanostructure has been studied by picosecond Raman spectroscopy at T= 300 K. Our experimental results demonstrate that at T= 300 K, for a 5-ps excitation laser pulse and a hole density of n_h ≅ 5 × 10¹⁷ cm^-3, transient hole drift velocity increases from zero to ≅ (3±0.7) × 10⁶ cm/sec when the applied electric field intensity increases from E=0 to 15 kV/cm. The transient hole drift velocity then becomes saturated at ≅(8 ±0.8)× 10⁶ cm/sec for the applied electric field intensity of E≥25 kV/cm and up to 65 kV/cm. These experimental results are in good agreement with Monte Carlo simulations. Simultaneous measurements of transient electron drift velocities indicate that transient electron drift velocities are about three times larger than the corresponding transient hole drift velocities.