LOW-RESISTANCE (SIMILAR-TO-1X10(-6)OMEGA-CM(2)) AU GE/PD OHMIC CONTACT TO N-AL0.5IN0.5P/

A Au (1000 Angstrom)/Ge (100 Angstrom)/Pd (100 Angstrom) contact schem e has been investigated to form low resistance Ohmic contact to n-Al0. 5In0.5P (E(g)=2.3 eV) with a minimum contact resistivity of about 1x10 (-6) Omega cm(2). The surface morphology of this contact remained smoo th after annealing at 425 degrees C for 1 min. Front side secondary io n mass spectrometry depth profiles of this contact structure under dif ferent annealing conditions were performed. It is found that the outdi ffusion of indium due to the reactions between the metallization and t he Al0.5In0.5P substrate in conjunction with the indiffusion of Ge int o the substrate is responsible for the Ohmic contact formation. The ge rmanide formation is believed to be responsible for the smooth surface morphology. The contact resistivity of this contact remained similar to 2x10(-6) Omega cm(2) after aging at 350 degrees C for 31 h. (C) 199 6 American Vacuum Society.