Large area vertical Ga2O3 Schottky diodes for X-ray detection

The Schottky barrier diodes were fabricated from a bulk Sn-doped (001) n-type Ga2O3 substrate with a Si-doped epitaxial layer grown by hydride vapor phase epitaxy (HVPE), which demonstrate a good response to X-rays. Circular metal contacts with diameters ranging from 50 to 1500 mu m and square metal contacts ranging from 100 x 100 mu m(2) to 1600 x 1600 mu m(2) were deposited on the wafer. The devices were characterized for their electrical performance including forward current-voltage (FIV), reverse current-voltage (RIV), and capacitance-voltage (CV) measurements. The best device showed a breakdown voltage of -804 V and the devices tested had an average ideality of 1.12. The devices exhibited a clear response to X-rays even at zero bias with an experimentally observed response time similar to 1.03 s and a linear response of detector signal to the X-ray dose rate. The experimentally observed device response time improved to similar to 0.25 s when bias voltage is applied. The device also survived a long-term stability test of over 2 h under a constant X-ray irradiation. The sensitivity and the lower limit of detection for X-ray by Ga2O3 epitaxial Schottky detectors were discussed and determined as 43.5 mu C/mGy cm(-2) at -200 V and 8.31 nGy(Air)/s, respectively.