Electrical and Structural Properties of Refractory Metal Multilayer Au/Ti/W/Ti Ohmic Contacts to n-GaAs

The ohmic contact characteristics of Au/Ti/W/Ti on n-GaAs were evaluated. Structural and electrical properties were studied by means of X-ray diffraction (XRD), Auger energy spectrum (AES) and an HP4145B analyzer. AES results show that W is a good barrier for preventing Ga and As from out-diffusing. Electrical measurement showed a minimum ohmic contact resistance of 5.5×10-6 Ωcm2. Thermal annealing results revealed that Au/Ti/W/Ti contact to GaAs treated by a (NH4)2S solution can withstand a temperature of 400°C for 15 h. This indicates that Au/Ti/W/Ti contact to (NH4)2S-treated GaAs may be suitable for practical application.