非对称耦合量子阱中亚毫米波辐射及其带间激子复合发光特性的理论研究

Theoretical studies of submillimeter radiation and near-infrared emission due to excitonic recombination in an asymmetric coupled-quantum-well structure

基于V形三能级模型运用密度矩阵方程研究了非对称耦合量子阱退局域化现象 ,并具体分析了导带中电子作阱间振荡所产生的亚毫米辐射和激子复合所产生的近红外发射物理过程 理论结果表明 :阱间电子波包振荡等效为一经典阻尼振子 ,其寿命由载流子与纵向光学声子散射时间和电子穿过势垒的渡越时间决定 ,所产生的亚毫米波辐射强度衰减仅与阱间阻尼系数有关 ,其线性服从洛仑兹分布 由带间激子复合所产生的近红外辐射频率随电子阱间振荡频率增加而减小 ,表现为量子限域斯塔克红移 ,即非对称量子阱在近红外发光区特性随反向偏压而变

In this paper the delocalized behaviours of an asymmetric coupled-quantum-well structure (a-CQWS) have been studied and the transfer process of the electrons between the two wells has been analyzed theoretically based on V-type system. We show that an electronic packet of coherent oscillation created by an ultrashort pulse can be viewed as a classical electronic dipole damping oscillator, whose lifetime depends strongly on both the electronic-tunneling transfer time and the carrier-longitudinal optial scattering time. The submillimeter radiative lifetime created by coherent oscillation of an electronic wave packet is related to the oscillation damping rate between the two wells but not to the exitonic recombination rate; the intensity in frequency domain has the Lorentz's profile. It is shown that the transiton frequency of near-infrared radiation generated by the excitonic recombination has a tunable characteristic. This result implys that the high-speed modulator and the tunable source in the near infrared-radiation region can be obtained from the asymmetric double-quantum well structure in the future optical communication.