ZnSSe-based ultra-violet photodiodes with extremely high detectivity

A noise study on a set of Zns 0.58 Se 0.42 UV photodiodes with 1 μm thick Al bonding pads selected from a 2 wafer was carried out. Based on their 1/f noise behaviors, they were divided into three groups. The noise spectral density, impulse response time, bandwidth, responsivity, dark current at reverse bias up to 12 V and zero bias resistance were determined for three typical detectors, i.e. one from each of the three groups. The uneven performance of these detectors is mostly likely due to the different damage level induced in the wire-bonding process. With thicker Al bonding pads of 1.5 μm, a detectivity as high as 7.1 x 10 14 cm Hz 1/2 W -1 has been achieved.