High-temperature I-V characteristics of the as-deposited and thermally annealed W/n-GaAs Schottky junctions fabricated by RF sputtering

Two W/n-GaAs Schottky diodes A and B were fabricated by sputtering using a RF power of 300 watt. The B diode was thermally treated at 390°C for 90 min. in Ar atmosphere. The temperature dependence of the characteristic diode parameters such as the rectification ratio (γ), ideality factor (n) and reverse saturation current (I₀ ) was established from the current-voltage (I-V) measurements performed in the temperature range 300-380 K on the as-deposited and thermally annealed diodes A and B, respectively. In the range of our experiments, the values of n varied over 1.86-1.43 in the as-deposited diode A and 1.11-1.32 in the thermally annealed diode B. More over, the room temperature value of γ in the thermally annealed diode was 500 times greater than that in the as-deposited diode. These fact indicated that the non-ideal character in the forward I-V characteristics was much more pronounced in the diode A than in the diode B. The thermionic emission (TE) and generation-recombination (GR) mechanisms contributed to the forward current transport in both the diodes, however, the GR to TE current ratio was 500 times smaller in the annealed diode B than in the diode A indicating that the TE and GR mechanism controlled the forward current in the diodes B and A, respectively. In the diode annealed at 390 C, the temperature dependence of the barrier height (φ_bo) calculated from TE reverse saturation current was described by the relation φ_bo=(0.87±0.01)-(5.4±2.3)×10^-4 T. Since, the TE current contribution in the diode A was very small compared to the total current, the φ_bo value in the as-deposited diode could not be determined precisely