Forward I-V characteristics of Pt/n-GaAs Schottky barrier contacts

The forward I-V characteristics of Pt/n-GaAs planar Schottky diodes and the effect of high temperature annealing on these characteristics have been investigated. Near-ideal (thermionic emission theory) I-V characteristics with an ideality factor n ≈ 1·00–1·09 and a barrier height φ_B ≈ 0·90–0·95 V are obtained for diodes made on as-received GaAs. On annealing at 350°C in vacuum, n remains practically unchanged although φ_B increases by ≈ 5–6 per cent and rather large currents are detected at voltages <0·3 V, which are attributed to the recombination centers created during alloying.For diodes made on GaAs which was preannealed in air at 350°C, non-ideal behavior is observed with φ_B ≈ 0·79–0·80 V and n ≈ 1·29. After annealing at 350°C in vacuum, n gradually decreases to 1·07 whereas φ_B increases to 0·96 V. Recombination currents are now observed at lower voltages. After further annealing at 350°C in air, n increases, φ_B decreases and recombination currents at lower voltages are no longer observed. A mechanism is proposed to explain the observed forward I-V characteristic behavior.