在過去數十年以砷化物半導體為材料製成的各種元件，已被廣泛的應用在電子、光電等重要產業中，尤其摻雜Sb的材料藉由多層磊晶下的type-II能帶結構，已經可以使發光波長範圍從1.1μm到3μm。但對於GaAs1-xSbx／GaAs量子井結構的能帶排列為type-I或type-II則尚未有定論，若為type-I的結構下，電子將只被限制在同一層的量子井結構中，若為type-II排列則可經由不同磊晶層中電子電洞的復合，其所放出的光波的能量可小於GaAsSb的能隙值(波長較長)，因此瞭解GaAs1-xSbx／GaAs界面間的結構和能帶結構是重要且必須的。在本論文中我們利用光調制光譜量測GaAs1-xSbx／GaAs異質接面因應力而產生的重電洞和輕電洞分裂，並經由理論計算出釋放應力的大小，發現Sb摻雜越多應力釋放程度越大。其次，利用拉曼光譜探討GaAs1-xSbx／GaAs界面的缺陷程度和GaAs1-xSbx磊晶層成長的好壞，得到當摻雜的Sb越多界面有越多的錯位缺陷，這解釋了應力是利用錯位成長的方式來釋放。
當量測多層量子井的光調制光譜時，在低能量會產生一個低頻率震盪的背景值，因此我們將調制方式改成非接觸式的電調制( CER)，減弱不必要的背景訊號，得到多層量子井的躍遷訊號，利用勞倫茲擬合得到導帶第一能階到價帶第一能階之躍遷值，證明GaAs1-xSbx／GaAs多層量子井確實是type-II能帶結構。

The application of long wavelength optoelectronic devices has become more and more extensively, and many different semiconductor structures, such as GaAsSb/GaAs single quantum well (QW), GaNAsSb/GaAs QW, InAs/GaAs quantum dots (QDs), GaAsSb-GaInAs/GaAs bilayer quantum well (BQW) , GaAsSb/GaAs multiple quantum wells (MQWs), and GaInNAs/GaAs MQWs have been developed. Especially, 1.3 μm wavelength laser diodes have attracted great attention due to its minimum loss in optical fiber communication. GaAsSb is a new material in this field and can be used for fiber optics communications, light emitting diodes, photodiodes et al. For GaAsSb/GaAs quantum wells, a majority of the band offset occurs in the valence band, and the valence band edge of GaAsSb is higher than that of GaAs. Because of slight conduction band offset, both weak type-I and weak type-II band alignment for GaAsSb/GaAs quantum wells have been reported in the literature. Type-I band alignment describes a conventional system, where electrons and holes are confined in the same layer. For type-II band alignment, electrons and holes confined in the different layers leads the spatial indirect transition in the narrow region near the interface. Therefore, to determine band alignment of GaAsSb/GaAs quantum wells is important for device design and theoretical modeling.
In this study, room-temperature photoreflectance (PR) and photoluminescence (PL) spectra were employed to investigate GaAsSb/GaAs heterojunctions. The band gap energy of unstrained GaAsSb and the confined level transitions of GaAsSb/GaAs MQWs were obtained from the PL spectra, and the PR spectra enabled the transition energies of strained GaAsSb from the conduction band edge to the heavy hole and the light hole band edges. Sb mole fraction and strain relaxation factor were determined by the valence-band splitting. With the same Sb mole fraction, the GaAs1-xSbx/GaAs MQWs H11 and H12 signals investigated by contactless electroreflectance(CER) spectroscopy is smaller than the band gap of GaAs1-xSbx with coherent strain. Therefore, the band alignment of coherent strained GaAsSb/GaAs MQWs must be type-II.

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