PHOTO : Materials - Epitaxy of III-V semiconductor structures using (111)B-grown quantum wells
Multiwell quantum structures GaAs-GaAlAs and GaInAs-GaAs PIN of orientation (111)B were grown by epitaxy. These structures have enabled our LPCNO partners to study the dynamics of electronic spin. For GaAs-GaAlAs structures, the application of an external electric field considerably increases the spin relaxation time, due to their particular orientation (111)B (figure a). On GaInAs-GaAs structures (figure b), the spin relaxation time can be imposed by an appropriate choice of indium concentration in the quantum wells, without needing an electric field. Here, this effect is obtained through compensation of the intrinsic spin relaxation mechanism Dresselhaus-Perel by the internal piezoelectric field present in these constrained wells.
Spin relaxation time of multi-quantum wells structures (111)B: (a) as a function of the applief electric field for GaAs/GaAlAs; (b) as a function of the In concentration in the wells for GaInAs/GaAs.
Quantum optoelectronics team at LPCNO, INSA, Toulouse
S. Azaizia, A. Balocchi, H. Carrère, P. Renucci, T. Amand, A. Arnoult, C.Fontaine, X. Marie, "Control of the electron spin relaxation by the built-in piezoelectric field in InGaAs quantum wells," Appl. Phys. Lett. 108, 082103, 2016. G. Wang, B.L. Liu, A. Balocchi, P. Renucci, C.R. Zhu, T. Amand, C. Fontaine, X. Marie, "Gate Control of the Electron Spin Diffusion Length in Semiconductor Quantum Wells," Nature Comm. 4, 2372, 2013.