Abstract
Au/Ge‐based Ohmic contacts to n‐type GaAs with an addition of a near‐noble‐metal, Ni, Pd, or Pt, have been studied. It was found that both the electrical characteristics and the material properties depend very much on this added metal. The material properties of the contacts after thermal alloying were studied using transmission electron microscopy and auger electron microscopy. The contact resistances obtained with different alloying conditions and their reliability have also been studied. It was found that Au/Ni/Ge had the roughest surface while Au/Pd/Ge had the highest contact resistance. The surface morphology was attributed to the difference in the sizes of the grains formed after Ohmic contact alloying. Au/Pt/Ge was found to be the best contact in terms of its electrical characteristics as well as its surface morphology.