Degradation of Gold-Germanium Ohmic Contact to n-GaAs

The metallurgical and electrical investigations were carried out on the Pt/Au-Ge and Ni/Au-Ge ohmic contacts to n-GaAs in focusing the degradation during aging. The characteristic structures in the alloyed regions and their metallurgical changes during aging (330°C) were examined by means of Electron Probe Micro-Analysis. The thick Pt and Ni films in the contact systems caused the reaction during aging to proceed. The degradation of the contact resistance during aging was found to take place with the progress of the metallurgical reaction. The details of the investigation including the discussions on the degradation mechanism will be described.