Ion beam mixing of alternate Au-Ge layer with GaAs

Ion beam mixing of alternate Au-Ge film structures deposited by e-beam evaporation on GaAs is carried out by 140, 125, and 80 keV Si+ ions at various doses. Mixing at room temperature between Au and Ge and between Au-Ge and GaAs is observed by employing Rutherford backscattering technique. Cross-sectional transmission electron microscopy revealed the presence of various amount of damage, depending on energy and dose of Si+ ions in the near surface region of GaAs. Optical microscopy showed smoother surface morphology of the ion mixed Au-Ge film; however, the contact thus made is found to be non-Ohmic. The non-Ohmic nature of the contact is attributed to the damage produced in GaAs due to ion bombardment. (author)