Abstract
近年來，由於光纖通訊在1.0至1.7微米波長範圍具有低色散及低損耗的特 性，使得此範圍波長的光源與檢光器之研究蓬勃發展，並已進入商業化生 產。而此段波長的檢光器材料目前均以InGaAs/InP為主，但欲得高性能檢 光器並不容易。本論以液相磊晶法成長一點七微米之砷化銦鎵(InGaAs)晶 膜於磷化鎵基板上，並摻入鉺(Er)雜質以研究其對材料的特性影響。進而 成長多層晶膜以研製PIN檢光器。砷化銦鎵晶膜與磷化銦基板間在未摻雜 質時可以得到近乎完全的晶格匹配，但加入鉺之後則呈現負的晶格不匹配 ，且隨著鉺摻入濃度之增加而逐漸增加。所有摻有鉺雜質的三元磊晶層皆 呈n-型導電性，且其電子濃度低於未摻雜時的一至二冪次大小。這結果顯 示了我們可以藉由鉺摻雜的加入而輕易得到高純度的砷化銦鎵磊晶層，免 除傳統上的需要長時間且高溫下來烘烤溶液。由低阻抗的霍爾量測可知當 鉺摻雜少於0.16重量百分比下，磊晶層移動率可以明顯增加，由光激光譜 的研究，我們發現發光波長，半高寬，光激光譜強度，隨著鉺摻雜的多寡 而有顯著的改變。在鉺摻為0.10重量百分比時具有最窄的半高寬為4.9meV ，當摻鉺量超過0.25重量百分比時，其光譜的Donor-Acceptor復合訊號會 消失，變成單一主訊號。我們同時也研製了鉺摻雜砷化銦鎵平面型檢光器 ，此元件的平面型面積約9.1E-5平方公分，在反向偏壓-5伏特下，暗電流 為0.21nA，電容質為 0.76pF，在波長1.53微米下，其敏感度為1.140A/W ，量子效率為92.5百分比，另外也研製了砷化銦鎵平面型檢光器為參考樣 本。 InGaAs eptiaxial layers were grown on (100)InP substrate by liquid-phase eptiaxy using supercooling technique. Doping effects on structure, electrical and optical properties of Er- doped 1.7um InGaAs eptiaxial layers have been examined. The nearly lattice match between the InGaAs eptiaxial layer and InP substrate can be obtained. The lattice mismatch between the InGaAs epitaxial layer and the InP substrate varies gradually with the amount of Er element in the grown solution. All the Er- doped samples still exhibit the n-type conduction and the carrier concentrations of the Er-doped InGaAs layers are one to two orders of magnitude lower than those of undoped layers. This result implies that the high purity InGaAs eptiaxial layers can be easily obtained with doping the Er element. We find that Hall mobilities evidentally increase with the amount of Er less than 0.16wt% in the low resistivity Hall measurement. The photoluminescence measurements have also been studied. The peak wavelength, the full width at half maximum and the intensity of photoluminescence spectra are dependent on the Er weight percent in the growth sloution. The full width at half maximum of 10K photoluminescence spectra have a minimum about 4.9meV occuring at Er wt%=0.107. The low carrier concentrations and narrow linewidths indicate that the impurities can be reduced effectively with the presence of Er dopant. At the same time, we also fabricate Er-doped 1.7um InGaAs PIN photodetector with planar area 9.1e-5 cm^2 under reverse bais -5V, the dark current and capacitance are 0.218nA and 0.765pF, respectively. The responsivity and quantum efficiency at wavelength 1.53um are 1.1409A/W and 92.5%, respectively.