砷化鎵鋁蕭基二極體的低溫製備及電性量測

Abstract

在本論文裡,主要探討經由低溫(77K)程序製備,以電流- 電壓(I-V)和電容-電壓(C-V)兩種方法量測的Au(或Pd)/AlxGa1-xAs金半接 面特性(x=0.28,0.30,0.32).對低溫製備的蕭基二極體而言,反向飽和電流 密度Jst降低了2~3倍,相對應在蕭基能障高度提升了40meV左右.以Au/ Al0.28Ga0.72As而言,Jst由6.4E-12下降至2.4E-12(安培/每平方公分),位 障(I-V)由1.02eV提升至1.05eV,位障(C-V)由1.17eV提升至1.20eV.此外, 經由比較(室溫製程與低溫製程)有摻雜Se的Al0.3Ga0.7As蕭基二極體反向 飽和電流與位障值,Se的摻雜可以用來改善AlGaAs磊晶薄膜的品質. In this study, we prepared and characterized Au( or Pd)/n-AlGaAs Schottky diodes by using low-temperature(LT;T=77 K) process, current-voltage(I-V), and capacitance-voltage(C-V) measurements. The leakage current density is reduced half for the diodes fabricated by low-temperature process compared with which fabricated at room temperature(RT), corresponding to an increase of Schottky barrierheight to be around 40 meV. For an Au/Al0.28Ga0.72As sample, the saturationcurrent density is reduced from 6.4E-12 for RT preparation to 2.4E-12(A/cm2) forLT processing. The C-V measurements for RT diodes indicate that the barrier height is raised from 1.17eV for RT diodes to 1.20eV for LT diodes. In addition,we demonstrated that Se doping can be used to improved the quality of AlGaAs films by comparing the barrier heights and saturation current densities of RT and LT Schottky diodes made on Al0.3Ga0.7As epilayers.