以砷化銦鎵/砷化鎵磊晶層作非合金化歐姆接觸之研究

Abstract

傳統的合金化接觸有一些缺點，諸如由於合金化所引起之表面粗糙稱為球 化現象，同時其製程需較高之溫度(350-450 ℃)。因此，吾人乃以分子束 磊晶法成長之砷化銦鎵結構作非合金化歐姆接觸之研究。然而，由於砷化 銦鎵和砷化鎵之間晶格常數的差異，因此砷化銦鎵/砷化鎵之異質結構不 易成長。本論文中，使用鈦/鉑/金及鎳/鍺/金兩種金屬膜，並對其在砷化 銦鎵上之歐姆接觸作物性、電性及熱穩定性之分析。於所有電性測量中， 以鈦/鉑/金膜未作熱處理前有最低之特徵接觸電阻值 2.00E-7Ω•cm**2 。於歐姆接觸之熱穩定性測量中，當退火溫度增加時由於銦鎵和金之間的 擴散使片電阻值下降而特徵接觸電阻值上昇。使用鎳/鍺/金膜時，退火後 之擴散現象更嚴重。因此，本論文研究之結論是鈦/鉑 /金膜為較好之非 合金化歐姆接觸金屬膜。 The conventions alloyed contacts for GaAs devices have some disadvantages such as it requires high temperature annealing, and the surface roughness called ball-up usually showed up during the alloyed process. In this thesis, the non-alloyed ohmic contacts on InGaAs layer grown on MBE had been investigated. Two different contact metals (Ti/Pt/Au, and Ni/Ge/ Au) were used. Both the material and electrical properties of the ohmic contacts were characterized and the thermal stability of these two films were studied. The specific contact resistance is 2.00E-7Ω•cm**2 when contact metals, Ti/Pt/Au, were used. As this contact were annealed, the sheet resistance decreases but the specific contact resistance increases with the annealing temperature. This is due to the interdiffusion of the In, Ga, and Au atoms during the annealing process. When Ni/ Ge/Au were used as the contact metals , the interdiffusion phenomenon becomes more severe than that of Ti/Pt/Au.