半導體微結構能階的探討及電子聲子交互作用的影響

Abstract

在本論文中,我們研究在不同結構中,電子-聲子交互作用對能階的影 響.論文的第一部份,我們引用李榮章先生等人所提出的微擾變分法,分別 計算量子位能阱及量子線中雜質能階的變化.在量子位能阱中,我們也計算 了從基態(1s)到激發態(2p)的耀遷(oscillationstrength).同時,我們也 考慮了電子-聲子交互作用對雜質束縛能的影響. 在論文的第二部份, 利用微擾變分的技巧,我們也計算了在強相干電子-聲子交互作用下, polaron 束縛能在三維空間及量子點中的變化. We have studied the polaron effect in various quantum structures. In part 1,a perturbative variational method within the effective-mass approximation of theground state and lowest excited states of a donor impurity in the quantum welland quantum wire is presented. The interaction of an electron with the confined bulk phonon is taken into account. In the case of quantum well, the line streng-ths of transitions from donor ground state to excited state of 2p-like symmetryare calculated. In part 2, by using the perturbative variational technique, the trial wavefunctions, which is able to yield correct polaron binding energy both in bulkand in a quantum dot, are employed as our polaron wave functions. Our calculatedbinding energy of strong-coupling polaron is in a good agreement with previousresults.