Wide spectral responses In x Ga 1–x N deep UV photomultiplier tube

We have designed and fabricated new photo‐tubes and photomultiplier tubes (PMTs) using In x Ga 1‐x N films as photocathodes. Longer spectral cutoffs were controlled with Indium compositions x, from 365 nm to 430 nm. The calibrated maximum quantum efficiency (QE) of 56% at 200 nm was achieved for x = 0.11 Indium composition in the photo‐tubes. Sharp cutoffs at around 160 nms were determined by window materials and those at around 400 nms were determined by the band gaps of the photocathodes. Gain and input/output linearity properties were confirmed to be very good for the PMTs. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)