Phonon Confinement and Electron Capture Time in Quantum Well

Abstract

Carrier capture times determine the rebuilding of an inversion population in a confinement region of semiconductor quantum well (QW) lasers and play a key role in their efficiency. Previous quantum-mechanical calculations [1-3] have revealed that the electron capture time oscillates as a function of QW width and that the most important scattering mechanism is due to electron-polar optical phonon (e—pop) interaction. So far, the polar optical phonon (pop) has been assumed to be a bulk phonon. In oscillation minima, the electron-electron (e—e) interaction-assisted capture time can improve the electron capture efficiency [3]. The electron capture constitutes a limiting factor in the carrier capture process into the QW because holes are captured in the QW first due to their larger effective mass [3, 4]. For the QW width smaller than 100 Α. [5], a confinement of phonons should be taken into account together with the electron confinement. We incorporate a model proposed by Ridley [6] into the previous calculations of the e-pop capture time [2, 3]. Ridley's model las introduced a new quasi-particle, the hybridon, to collect three types of optical phonon modes; longitudinal, transversal and interface; in the semiconductor QW. An electron-hybridon (e—hy) interaction is considered only in the QW region, whereas over the AlGaAs barrier we still take into consideration the interaction of an electron with the bulk pop owing to the large barrier width [5]. We will abbreviate this mixed capture time as the e—hy+pop capture rate. In Ref. [5], for the GaΑs/Gax In1x As QW structure with x = 0.3 and the QW width equal to 50 A, the e—hy+pop interaction-induced capture rate from the