Figure 2. Detector damage comparison from irradiation at 193 nm.
The radiation damage characteristic of four different photodiodes, PtSi, nitrided-Si, UV Si, and GaN, were studied with a 193 nm excimer laser up to a dosage of 106 J/cm2. The responsivity of UV Si photodiode reduced to 60 % of its original responsivity with 1000 J/cm2 of dosage while the GaN photodiode responsivity decreased to 40 % of its original value with only 10 J/cm2 of dosage. The PtSi and nitrided-Si photodiodes are less damaged by radiation and showed about 10 % change in responsivity with a dosage of 105 J/cm2.