Unified description of electron spin relaxation in (110)-oriented III–V semiconductor quantum wells

III–V semiconductor quantum wells (QWs) with (110) orientation are expected to serve as a platform for spintronic devices due to their ability to exhibit prolonged electron spin-relaxation times to the order of nanoseconds even at room temperature. Although various spin-relaxation mechanisms have been proposed and the spin-relaxation time has been discussed qualitatively, quantitative clarification of the contribution of each mechanism is crucial. In this study, we demonstrate that the electron spin-relaxation times calculated as a function of quantized energy, temperature, and electron density in GaAs/AlGaAs (110) QWs, accounting for all potential spin-relaxation mechanisms (Elliott–Yafet, intersubband spin relaxation, and exciton spin relaxation), show good agreement with experimental data. Our results reveal that the contribution of each spin-relaxation mechanism to the total spin-relaxation time in the (110) QWs can be quantitatively identified and that the dominant mechanism depends on the specific conditions. These findings will facilitate the design of suitable QW structures for spintronic devices and enable precise estimation of the spin-relaxation time under operating conditions of (110) QW-based spintronic devices.