Electrical transport and low frequency noise characteristics of Au/n-GaAs Schottky diodes containing InAs quantum dots
Au/n-GaAs Schottky diodes, containing layers of InAs quantum dots (QDs), are investigated by measuring the forward current-voltage characteristics in the temperature range of 77-300 K and low frequency noise at room temperature. The zero-bias barrier height decreases and the ideality factor increases with decreasing temperature, and the ideality factor was found to follow the T0-effect. The departure from the ideal thermionic-emission diffusion model was interpreted in terms of inhomogeneous Schottky contact with a Gaussian distribution of barrier heights. The excess current at small biases, observed in diodes containing layers of InAs QDs, was attributed to small patches of reduced barrier height. In the diode without QDs, the noise intensity SI shows 1/f behaviour and is proportional to I2F, which is explained by modulation of the barrier height due to trapping processes in interface states. In diodes containing InAs QDs, SI shows 1/fggr (with ggr < 1) behaviour and is proportional to I2F in the high current range, which is explained by generation of band tail states with exponential energy distribution in the GaAs layer due to the QD formation. In the low current range, SI increases faster than I2F due to contribution to the noise of patches of reduced barrier height.