Mechanism of dislocation-governed charge transport in Schottky diodes based on gallium nitride

A mechanism of charge transport in Au-TiBx-n-GaN Schottky diodes with a space charge region considerably exceeding the de Broglie wavelength in GaN is studied. Analysis of temperature dependences of current-voltage (I-V) characteristics of forward-biased Schottky barriers showed that, in the temperature range 80-380 K, the charge transport is performed by tunneling along dislocations intersecting the space charge region. Estimation of dislocation density rho by the I-V characteristics, in accordance with a model of tunneling along the dislocation line, gives the value rho approximate to 1.7 x 10(7) cm(-2), which is close in magnitude to the dislocation density measured by X-ray diffractometry.