PdGe-based ohmic contacts to high-low doped n-GaAs with and without undoped cap layer

摘要

We report the ohmic contact formation mechanism for a low-contact resistance PdGe-based system on high-low doped GaAs with and without undoped cap layer annealed in the temperature range of 380-450 degrees C. The lowest average specific contact resistances of the Pd/Ge/Ti/Pt ohmic contacts with and without undoped cap layer after annealing at 400 degrees C were 5.3 x 10(-6) Omega cm(2) and 2.4 x 10(-6) Omega cm(2), respectively. And the lowest average specific contact resistances of the Pd/Ge/Ti/Pt/Au ohmic contacts with and without undoped cap layer after annealing at 380 degrees C were 3.5 x 10(-6) Omega cm(2) and 3.4 x 10(-6) Omega cm(2), respectively. For the Pd/Ge/Ti/Pt contact without undoped cap layer, the x-ray diffraction, cross-sectional scanning electron microscopy and Auger electron spectroscopy were utilized in this study. The Pd/Ge/Ti/Pt ohmic contact without undoped cap layer was thermally stable after isothermal annealing at 400 degrees C for 6 h. [References: 18]