Quantitative assessment of the effects of carrier screening on the average electric field in a GaAs-based p–i–n nanostructure under subpicosecond laser excitation

Abstract

We have used electric-field-induced Raman scattering to quantitatively assess the effects of carrier screening on the average electric fields in a GaAs-based p–i–n nanostructure semiconductor under subpicosecond laser photoexcitation. Our experimental results demonstrated that the effects of carrier screening on the average electric field were negligible for a photoexcited electron–hole pair density of n⩽1015 cm−3. As the density of photoexcited carriers increased, we observed a significant decrease of the average electric field. In particular, for n=1018 cm−3, a decrease of electric field of about 50% was found. All of these experimental results were explained by ensemble Monte Carlo simulations and very good agreement has been obtained.

Subpicosecond time-resolved Raman studies of field-induced transient transport in an InxGa1−xAs-based p-i-n semiconductor nanostructure

“…23,24 The effective electric field intensity was determined by using the Franz-Keldysh effect, as demonstrated in Ref. 25. The nonequilibrium elec-tron distributions are directly measured in a way similar to Ref.…”

Subpicosecond Raman studies of electric-field-induced optical phonon instability in an In0.53Ga0.47As-based semiconductor nanostructure

“…This is because the spatial separation of electrons and holes during the transient generates an electric field which tends to oppose the applied electric field. In this section, in a similar way to reference [18], we describe briefly how the average effective electric fields under various applied electric field intensities and photoexcited electron-hole pair densities were obtained. When an electric field is applied to a semiconductor, the electric field separates electronhole pairs and modifies their wavefunctions from Bloch to Airy type.…”

Subpicosecond transient Raman scattering studies of field-induced electron transport in an In0.53Ga0.47As based p–i–n nanostructure: direct observation of the effects of electron momentum randomization

“…This scattering configuration ensures the detection of a scattered light signal from only spin-density fluctuations (SDF) [23,24]. The effective electric field intensity during laser irradiation was determined from the Franz-Keldysh effect, as demonstrated in [31]. One important advantage of probing non-equilibrium excitations with Raman spectroscopy in semiconductors is that, since it detects a Raman signal only when excitation photons are present, the time resolution is essentially limited by the pulse width of the excitation laser and not by the response of the detection system.…”