Effective Manipulation of Spin Dynamics by Polarization Electric Field in InGaN/GaN Quantum Wells at Room Temperature

Abstract

III‐nitride wide bandgap semiconductors are favorable materials for developing room temperature spintronic devices. The effective manipulation of spin dynamics is a critical request to realize spin field‐effect transistor (FET). In this work, the dependence of the spin relaxation time on external strain‐induced polarization electric field is investigated in InGaN/GaN multiple quantum wells (MQWs) by time‐resolved Kerr rotation spectroscopy. Owing to the almost canceled two different spin–orbit coupling (SOC), the spin relaxation time as long as 311 ps in the MQWs is obtained at room temperature, being much longer than that in bulk GaN. Furthermore, upon applying an external uniaxial strain, the spin relaxation time decreases sensitively, which originates from the breaking of the SU (2) symmetry. The extracted ratio of the SOC coefficients shows a linear dependence on the external strain, confirming the essential role of the polarization electric field. This effective manipulation of the spin relaxation time sheds light on GaN‐based nonballistic spin FET working at room temperature.

Piezoelectric manipulation of spin–orbit coupling in a Wurtzite heterostructure

“…31 The spin relaxation time in the (In, Ga)N/GaN quantum wells can also be controlled by external strain. 35 In these experiments, the externally supplied strain was very small (<0.1%), and therefore, it was difficult to observe notable piezoelectric manipulation of SOC, as revealed here. However, there are several qualitative agreements between these results and ours.…”

“…A micrometric system is usually utilized to exert uniaxial strain on the heterostructure. 31,35 By fixing the device on the sample stage, the micrometric screw on the bottom center of the sample stage is used to bend the device by moving the screw. By recording the moving distance, uniaxial strain can be calculated from basic geometrical parameters of the sample.…”

“…31 Moreover, compared with Rashba coupling, the more sensitive strain-dependence of Dresselhaus SOC leads to the reduction in the ratio α R / α D by compressive strain, which is also consistent with the spin relaxation time measurements in (In, Ga)N/GaN multiple quantum wells. 35…”

Half‐Metallic Heusler Alloy/GaN Heterostructure for Semiconductor Spintronics Devices

“…[3][4][5][6] The growth of GaN quantum dots [7,8] and GaN nanowires [7,9,10] has recently been explored for single-photon emitters in quantum information processing applications, and full-color micro-LEDs have been reported in monolithically stacked Eu-doped GaN and InGaN quantum well heterostructures. [11] Because of the intrinsically weak spin-orbit coupling in GaN, [12][13][14] the possibility of semiconductor spintronic devices such as a spin LED [15][16][17] and spin field-effect transistor [18,19] has also emerged in the field of GaN systems. Thus far, it has been demonstrated, even at room temperature, electrical spin injection into GaN in LED structures [20][21][22][23] and three-or four-terminal lateral device structures.…”

Electrical Spin Injection into the 2D Electron Gas in AlN/GaN Heterostructures with Ultrathin AlN Tunnel Barrier

“…[ 12,13 ] Meanwhile, 2DEG in GaN‐based heterostructures may provide more opportunity for the realization of spin manipulation with tunable SOC. [ 14,15 ] However, up to now, the complete SFET following the Datta–Das model has only been realized in InGaAs‐based 2DEG. [ 16,17 ] One is based on a ferromagnet (FM)/insulator tunneling junction while the other is based on quantum point contact.…”