X-ray detection with zinc-blende (cubic) GaN Schottky diodes

The room temperature X-ray responses as functions of time of two n type cubic GaN Schottky diodes (200?µm and 400?µm diameters) are reported. The current densities as functions of time for both diodes showed fast turn-on transients and increases in current density when illuminated with X-ray photons of energy up to 35?keV. The diodes were also electrically characterized: capacitance, implied depletion width and dark current measurements as functions of applied bias at room temperature are presented. At -5?V reverse bias, the capacitances of the diodes were measured to be (84.05?±?0.01) pF and (121.67?±?0.02) pF, respectively. At -5?V reverse bias, the dark current densities of the diodes were measured to be (347.2?±?0.4) mA cm-2 and (189.0?±?0.2) mA cm-2, respectively. The Schottky barrier heights of the devices (0.52?±?0.07) eV and (0.63?±?0.09) eV, respectively, were extracted from the forward dark current characteristics.