DP Mechanism Research Articles

Electron spin relaxation beyond D'yakonov–Perel’ interaction in GaAs/AlGaAs quantum wells

To study electron spin relaxation mechanisms in GaAs/AlGaAs quantum wells (QWs), undoped and n-doped (1 0 0) and (1 1 0) QWs with different well width and doping density are prepared and measured. The temperature dependence of electron spin relaxation time τ s in n-doped (1 0 0) QWs above 30 K is shown to be in good agreement with what is expected from the D'yakonov–Perel’ (DP) mechanism. In (1 1 0) QWs, a 30-fold increase of τ s over (1 0 0) QWs at room temperature is observed. This dramatic increase is explained by the suppression of the DP mechanism. The remaining spin relaxation processes in (1 1 0) QWs are discussed.

Spin-lattice relaxation in p-type gallium arsenide single crystals.

An optical-pumping technique is used to measure the spin-relaxation time of photogenerated conduction electrons in several p-type GaAs single crystals doped with various amounts of acceptors in the 1.7--300 K temperature range. Our experimental results are compared with those of the literature and with the predictions of the existing theoretical calculations. From about 10 K, the Bir-Aronov-Pikus (BAP) mechanism is found to be relevant for moderately doped ${(10}^{17}$--${10}^{18}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$), up to about 150 K, or degenerate (up to 300 K) semiconductors, using the electronic temperature, deduced from the luminescence spectra, rather than the sample temperature. The D'yakonov-Perel' (DP) process was found to be active above 200 K for moderately doped samples and from about 80 K to room temperature for samples doped in the (1.6--6)\ifmmode\times\else\texttimes\fi{}${10}^{16}$-${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ acceptor-concentration range. Our original results obtained at liquid-helium temperatures at whatever the doping level cannot be explained either by the DP mechanism or by the BAP process.