固態源分子束磊晶成長含磷化合物半導體之研究

Abstract

因為可見光與高速光電元件的應用，近年來眾多研究者專注於三五磷化合物的發展。本論文將以固態源分子束磊晶系統生長與砷化鎵基底晶格匹配，但組成不同的磷化銦鎵鋁與不同的異質結構磊晶層。藉由精確的掌控三腔閥門式磷裂解腔，我們先研究磷化銦鎵鋁的光電特性。在高溫的裂解溫度下，會產生較多的二元磷分子，其所磊晶出的磷化銦鎵，在光螢光與反射實驗結果中，具有較低的排序效應與能帶隙。磷化銦鎵鋁的施體﹝矽﹞與受體﹝鈹﹞滲雜濃度不會因基底偏角度的大小而有所改變，此點是與有機金屬化學氣相磊晶系統是不同的。而不同的矽滲雜磷化銦鎵鋁施體濃度與磷裂解溫度、砷化鎵基底溫度的關係也被研究。因為磷裂解溫度與磷分子的化學鍵結有關，我們認為矽滲雜磷化銦鎵鋁施體濃度的增加與降低磷裂解溫度相關的原因是導因於藏在磷中氧的污染減少之故。採用﹝磷化銦﹞/﹝磷化鎵﹞短周期超晶格的異質結構，此種結構的量子井會因強列相分離的自然形成造成量子線的現象，其發光波長會因不同的成長條件而改變，改變不同的間歇生長期間，其發光波長會有隨溫度改變而不同偏移的特性；運用大角度的砷化鎵基底可有效的抑制﹝磷化銦﹞/﹝磷化鎵﹞橫向組成調變。各種實驗上證明，以固態源分子束磊晶系統生長含磷化合物半導體或光電元件，將在未來研究與生產應用中有廣泛的用途。

Recent researches on semiconductors have been focusing on III-V phosphides due to their potential optoelectronic applications in the visible and high-speed devices. This thesis studies In0.5(GaxAl1-x)0.5P (x=0~1) thin films lattice-matched to GaAs substrates and different heterostructures grown by all solid source molecular beam epitaxy (SSMBE) over the entire alloys. By precisely controlling the three-zone valved phosphorus cracker cell, the optoelectronic properties of the In0.5(GaxAl1-x)0.5P epilayers grown were investigated. The temperature dependent photoluminescence and photoreflectance showed that the ordering effect and the energy gap of InGaP epilayers decreased as the cracker temperature increased. Contradict to the results reported in the Metal-Organic Chemical Vapor Deposition (MOCVD) growth, the incorporation efficiency of both donor (Si) and acceptor (Be) showed no apparent variation while changing the substrate misorientation. The dependence of Si doping efficiency in the InGaAlP epilayers on the cracker temperature and the growth temperature was also studied. Since the cracker temperature changes mainly the P4/P2 flux ratio, the enhancement of the effective carrier concentration in Si-doped InGaAlP with higher P4/P2 flux ratio is attributed to the reduction of oxygen contamination. A strong phase separation can be induced in the growth of (InP)2/(GaP)2 short-period superlattices (SPS), which if inserted in a general quantum well structure can form a quantum-wire like heterostructure. Most importantly, an alterable temperature dependent wavelength shift was observed in the SPS structure growth, which can be changed if the growth interruption was adjusted. A larger substrate tilt angle can suppress the lateral composition modulation in (InP)/(GaP) heterostructures. The observed high quality phosphide epilayers suggests that the SSMBE system is reliable and useful for many practical applications.