A Novel Pd-based Ohmic Contact System for n-type GaAs: A Structural, Morphological and Electrical Investigation

A novel Pd-based Ohmic contact system is developed for n-GaAs. Metallization samples are annealed at various temperatures and systematically characterized using current-voltage (I-V) measurements, Tencor surface profilometry measurements, Scanning electron microscopy (SEM) and Secondary ion mass spectrometry (SIMS). Tencor measurements and SEM are employed to investigate the surface morphology of the contacts. The contact depth profiles are analyzed by SIMS. Effects of metallization thicknesses on contact properties are also presented. Conversion from Schottky to Ohmic behaviour of the contacts is examined using I-V measurements. Contact resistivities, ρc, of the proposed metallization are measured utilizing a Transmission Line Model (TLM) structure. Annealing at 3600C for 30 min yielded a lowest ρc of ~3.26x10-5 Ω-cm2 on 2x1018 cm-3 n-GaAs.