Quantum efficiency of solar-blind semiconductor photodiodes in the far ultraviolet

摘要

A difficulty in diverse metrological applications is the measurement of relatively low intensity ultraviolet radiation signals in the presence of an intense visible radiation background. The development of a detector technology that combines the high efficiency and ease of use found in Si photodiodes with the solar-blind characteristics of many photoemissive devices would offer an ideal solution to this problem. Wide bandgap semiconductors (e.g. SiC, GaN and AlGaN) should combine sensitivity comparable to Si photodiodes with solar-blind response. We present ultraviolet quantum efficiency measurements of AlGaN Schottky and GaN p-i-n photodiodes demonstrating responsivity in the far ultraviolet to wavelengths as short as 116 nm (AlGaN Schottky devices) or 180 nm (GaN p-i-n devices) and several orders of magnitude reduction in efficiency for photon energies below the bandgap. The bandgap for GaN corresponds to 365 nm wavelength, and AlGaN devices exhibit cut-off wavelengths as short as 260 nm.