Terahertz quantum cascade laser with an X-valley-based injector

Abstract

We present a novel terahertz (THz) quantum cascade laser (QCL) design where Γ-valley states are used for lasing transition and X-valley states—in particular, Xz-states—are used as injector subbands. Since the lasing states in our proposed structure are populated and depopulated mainly through the interface roughness assisted Γ-Xz electron scattering, we present a model to describe this intervalley carrier transport. In the injector region of the proposed THz QCL, we use a quaternary AlGaAsP material to introduce tensile strain, which plays a crucial role in increasing the gain. To compensate the strain per period, we propose to grow the periodic heterostructure on a GaAs0.94P0.06 virtual substrate. To simulate the carrier transport and hence calculate the gain and lasing performance of the proposed THz QCL, we use a simplified density matrix formalism that considers resonant tunneling, dephasing, and the important intersubband scattering mechanisms. Since electron temperature significantly varies from lattice temperature for QCLs, we take their difference into account using the kinetic energy balance method. We show that the proposed structure is capable of lasing up to a maximum lattice temperature of ∼119 K at 4.8 THz. For future improvements of the device, we identify major performance-degrading factors of the proposed design.

Toward Hot Carrier Extraction in Intervalley Photovoltaic Devices

“…A number of possible methods for mitigation of the momentum dependence exist. Intervalley real space transfer has been demonstrated in III-V zincblende materials, , with applications of such resonant tunneling including terahertz quantum cascade lasers . Of particular note, interface roughness at heterojunctions has been observed to induce breakdown of strict momentum conditions in intervalley transitions .…”

Температурная Зависимость Порогового Тока И Выходной Мощности Квантово-Каскадного Лазера С Частотой Генерации 3.3 ТГц

“…[9,10]. Другой подход основан на разработке новых схем работы ТГц ККЛ на основе GaAs/AlGaAs, где апробируются новые способы инжекции электронов [11], дизайны с подавлением паразитных каналов проводимости [12] и использование −X междолинного транспорта в GaAs [13].…”