Fabrication and Characterization of Modulation-Doped ZnSe/(Zn,Cd)Se (110) Quantum Wells: A New System for Spin Coherence Studies

Abstract

We describe the growth of modulation-doped ZnSe/(Zn,Cd)Se quantum wells on (110) GaAs substrates. Unlike the well-known protocol for the epitaxy of ZnSe-based quantum structures on (001) GaAs, we find that the fabrication of quantum well structures on (110) GaAs requires significantly different growth conditions and sample architecture. We use magnetotransport measurements to confirm the formation of a two-dimensional electron gas in these samples, and then measure transverse electron spin relaxation times using time-resolved Faraday rotation. In contrast to expectations based upon known spin relaxation mechanisms, we find surprisingly little difference between the spin lifetimes in these (110)-oriented samples in comparison with (100)-oriented control samples.

Spin dynamics in semiconductors

“…Spin relaxation in (110) ZnSe quantum wells was studied in Ref. [685], where behaviors quite different from that in GaAs (110) quantum wells were found. Spin lifetime was reported to decrease monotonically with increasing temperature in CdTe quantum wells [535].…”

Interplay of Rashba/Dresselhaus spin splittings probed by photogalvanic spectroscopy –A review

“…Quantum well structures prepared on (110)’oriented GaAs substrates are of particular interest because in QWs of this orientation and special design extraordinarily slow spin dephasing can be achieved. Spin lifetimes up to several nanoseconds or even submicroseconds () have been reported in GaAs and other III–V semiconductor‐based heterostructures, for review see, e.g., (). As discussed in Section , in structures of this orientation the effective magnetic field induced by the BIA points along the growth axis and does not lead to the Dyakonov–Perel relaxation of spins oriented along this direction.…”

Spin coherence of electrons and holes in ZnSe‐based quantum wells studied by pump–probe Kerr rotation

“…Spin injection of electrons from GaAs to ZnSe epilayers with conserving their spin coherence has been identified by pump–probe Faraday rotation . In (Zn,Cd)Se/ZnSe QWs with electron density of cm −2 the electron spin dephasing time of 4 ns at liquid helium temperatures has been found, and spin beats in pump–probe Faraday rotation have been detected up to room temperature . While in undoped (Zn,Cd)Se/ZnSe QWs spin dynamics was very fast, 10 ps only at 5 K and increases to 200 ps at 240 K. Similar appearances have been reported for undoped ZnSe/(Zn,Mg)(S,Se) QWs ().…”