InAlGaAs和GaAs的光調制反射光譜與Pd/GaAs的蕭特基接面之研究

Abstract

本論文主要探討InAlGaAs、GaAs的光調制反射光譜特性及及分析低溫蒸鍍 和室溫蒸鍍製備的 Pd/GaAs 蕭特基接面電流-電壓特性。我們以光調制反 射光譜技術分析測量各種組成的 InAlGaAs的能隙躍遷及Franz-Keldysh振 盪。同樣地，我們以光調制反射光譜技術測量各種長晶條件下製備之GaAs 晶膜，而據以分析GaAs晶膜之雜質成份與載子濃度。低溫蒸鍍製備的蕭特 基接面與室溫蒸鍍製備的蕭特基接面的研究方面，實驗結果顯顯示低溫蒸 鍍製備的蕭特基接面具有較高的蕭特基位障、較低的反向飽和電流與較接 近一的理想因子，以Pd/GaAs接面言， 77K下製備者較室溫下製備者蕭特 基位障提升0.15V，而前者的理想因子為1.03，後者的理想因子為1.12。 In this thesis, we studied the properties of InAlGaAs and and GaAs epilayers and the characteristics of Pd/GaAs Schottky junctions.We employed photoreflectance (PR) technique to analyze the energy level transitions and the Franz-Keldysh oscillations (FKO) of InAlGaAs epilayers with various compositions. We also applied the PR method to examine the impurity components and to measure the carrier concentration of GaAs epilayers which were prepared under various growth conditions. The Pd/GaAs Schottky junctions were fabricated by thermal evaporation with substrate temperature of 77K and 300K. The current- voltage (I-V) characterization of Schottky junctions revealed that the cryogenic process provided the advantages of higher Schottky barrier height, lower saturation current density, and better ideality factor than the room temperature process.For Pd/GaAs junction, the Schottky barrier height was raised up from 0.84 to 0.99V, the saturation current density was lowered down from 5.6E-9 to 2.3E-11 A/cm2, and the factor was reduced from 1.12 to 1.03 as compared the cryogenic cryogenic with room-temperature fabrication processes.