High-Detectivity Ultraviolet Photodetectors with Epitaxial GaN on Si(111)

Fabrication and systematic characterization of GaN/Si(111)-based visible-blind ultraviolet photodetectors, with Pt/Au contacts, is reported. We demonstrate a record-high detectivity of 4.93x10
¹⁴
Jones, for bias voltages exceeding V
B
= 14 V. The high detectivity is obtained due to extremely low dark current (~ pA, even for V
B
= 40 V), and high responsivity, in the wavelength range of 320 nm - 380 nm. The highest responsivity obtained for the measured devices is 255 A/W, at V
B
= 50 V and excitation wavelength of 353 nm.