Improved cold finger and chuck design of a cryo-prober for quantum efficiency measurement using backside illumination for HgCdTe IR diodes

We present a low temperature 80 K cryo-prober methodology for measuring quantum efficiency (QE) in the backside illumination mode suitable for characterizing infrared (IR) detectors at the wafer level without using a readout integrated circuit (ROIC) or fan-out on chip carriers. The method involves the design of a specific device-mounting chuck in such a way that there is a gap beneath it, which is used for reflecting the incoming IR radiation from the side window to the top (or the backside of the device). Sample experimental results for HgCdTe IR diodes have been demonstrated using the said method.