International Radiation Detectors, Inc.

Performance Characteristics

In addition to extreme radiation hardness, SXUV photodiodes are also resistant to environmental contaminants such as moisture. SXUV photodiodes show no change in 254 nm responsivity after exposure to 100% relative humidity for a period of four weeks.

Accelerated testing was performed on the SXUV-100 photodiodes to verify reliability. The diodes were subjected to 113 ⁰C ambient temperature under a reverse bias of 10 V. The result was no increase in dark current after continuous operation at this high temperature for one week which is indicative of long term room temperature stability. Note that reverse bias was used in this test as SXUV photodiodes are recommended to be used with reverse bias for all excimer laser applications.

Responsivity uniformity of 1 cm x 1 cm active area SXUV photodiodes (model # SXUV-100) was found to be within ± 2% when tested at 254, 162, 120 and 10 nm. Figure 1 shows the spatial responsivity uniformity for the SXUV-100 photodiode at 121.6 nm with 1 mm diameter beam.

Fig. 1: Spatial responsivity uniformity of the SXUV-100 photodiode at 121.6 nm

Figure 2 shows temperature dependence of the shunt resistance. The shunt resistance was found to decrease by a factor of 2 for every 6 ⁰C rise in temperature.

Fig. 2: Temperature dependence of Shunt Resistance of the SXUV-100 photodiode

Figure 3 shows the temperature dependence of the photodiode responsivity at 254 nm. Typically, the responsivity was found to decrease by 0.1% per degree Celsius. Because the SXUV photodiodes have high surface recombination (indicated by their low responsivity), the decrease in responsivity at higher temperatures is presumably caused by an increase in the surface recombination velocity.

Fig. 3: Change in 254 nm responsivity of SXUV series diodes with temperature

SXUV-100 photodiodes are currently in the field. Some SXUV photodiodes have seen use in feedback loops to control the energy of excimer laser pulses.