We have prepared the Au/Ti/Al2O3/n-GaAs structures and investigated their current-voltage (I-V) characteristics with the temperature (in 20-320K range) as a parameter, and current-temperature (I-T) characteristics with bias voltage as a parameter. The ultrathin Al2O3 metal-oxide layer on the n-GaAs substrate has been formed by atomic layer deposition (ALD) method. Ti(10nm) rectifying contacts have been fabricated on Al2O3/n-GaAs structure by DC magnetron sputtering. The ideality factor value has remained between 1.10-1.06 from 130 K to 320 K. The barrier height (BH) value has increased with a slope of alpha = -0.31 meV/K from 320 K to 110 K. Then, it has been seen that the decrease in the BH value from 110 K to 20 K obeys a double Gaussian distribution (GD) of the BHs due to the BH inhomogeneity. The experimental I-T characteristics have been interpreted by plotting the theoretical I-T characteristics with and without the GD based on the TE current theory at each bias voltage. Moreover, the BH values have been also determined from the Richardson curves plotted using the I-T data at each forward and reverse bias voltage. It has been observed that the BH reduction is higher under reverse bias voltage than under forward bias voltage regime due to the barrier inhomogeneity which is not recommended for the Schottky diode being a rectifying device.