Radiation induced luminescence of the CdZnTe substrate in HgCdTe detectors for WFC3

Proton induced luminescence in the HgCdTe detectors for the Wide Field Camera 3 instrument has been investigated. A radiation experiment has been conducted to localize the source of the luminescence. Conclusive evidence is shown that the luminescence originates in the CdZnTe substrate and propagates toward HgCdTe photodiodes as ~800 nm radiation. Luminescence is proportional to the proton energy deposited in the substrate. Subsequent testing of detectors with the substrate removed confirmed that substrate removal completely eliminates proton induced luminescence.