Figure 4: Spin Lifetime in the gate-control device.

(a) Photoluminescence intensity (colour code in arbitrary units) as a function of both time and photon energy for a reverse bias V=5 volts. The white curve represents the PL intensity as a function of time when the emission is spectrally integrated. The decay time of this PL dynamics corresponds to the electron lifetime τ. (b) PL circular polarization degree P_c (colour code from P_c=0 to P_c=0.30) as a function of both time and photon energy for a reverse bias V=5 volts. P_c=(I⁺−I⁻)/(I⁺+I⁻), where I⁺ and I⁻ are the PL circular components, respectively, co- and counter-polarized with the incident laser beam. The white curve represents P_c as a function of time when the emission is spectrally integrated. The decay time of this P_c dynamics corresponds to the electron spin-relaxation time τ_s. (c) Gate control of the electron spin lifetime T_s. (d) Gate control of the spin-relaxation time τ_s.