Electrical transport and current properties of rare-earth dysprosium Schottky electrode on p-type GaN at various annealing temperatures

Abstract

The electrical and current transport properties of rapidly annealed Dy/p-GaN SBD are probed by I–V and C–V techniques. The estimated barrier heights (BH) of as-deposited and 200 °C annealed SBDs are 0.80 eV ( I–V)/0.93 eV (C–V) and 0.87 eV (I–V)/1.03 eV (C–V). However, the BH rises to 0.99 eV (I–V)/ 1.18 eV(C–V) and then slightly deceases to 0.92 eV (I–V)/1.03 eV (C–V) after annealing at 300 °C and 400 °C. The utmost BH is attained after annealing at 300 °C and thus the optimum annealing for SBD is 300 °C. By applying Cheung’s functions, the series resistance of the SBD is estimated. The BHs estimated by I–V, Cheung’s and ΨS–V plot are closely matched; hence the techniques used here are consistency and validity. The interface state density of the as-deposited and annealed contacts are calculated and we found that the NSS decreases up to 300 °C annealing and then slightly increases after annealing at 400 °C. Analysis indicates that ohmic and space charge limited conduction mechanisms are found at low and higher voltages in forward-bias irrespective of annealing temperatures. Our experimental results demonstrate that the Poole–Frenkel emission is leading under the reverse bias of Dy/p-GaN SBD at all annealing temperatures.