Thermal annealing effects on I-V-T characteristics of sputtered Cr/n-GaAs diodes

Sputtered Cr/n-GaAs Schottky diodes have been prepared and annealed at 200 and 400 deg. C. The current-voltage (I-V) characteristics of the as-deposited and annealed diodes have been measured in the temperature range of 60-320 K with steps of 20 K. The effect of thermal annealing on the temperature-dependent I-V characteristics of the diodes has been investigated experimentally. The ideality factor and barrier height (BH) values for 400 deg. C annealed diode approximately remain unchanged from 120 to 320 K, and those of the as-deposited sample from 160 to 320 K. The departures from ideality at low temperatures have been ascribed to the lateral fluctuations of the BH. The BH values of 0.61 and 0.74 eV for the as-deposited and 400 deg. C annealed diodes were obtained at room temperature, respectively. A Richardson constant value of 9.83 A cm-2 K-2 for 400 deg. C annealed Schottky diode, which is in close agreement with the known value of 8.16 A cm-2 K-2 for n-type GaAs. Furthermore, T0 anomaly values of 15.52, 10.68 and 5.35 for the as-deposited and 200 and 400 deg. C annealed diodes were obtained from the nT versus T plots. Thus, it has been seen that the interface structure and quality improve by the thermal annealing at 400 deg. C.