Non-linear behaviour of large-area avalanche photodiodes

Abstract

The characterisation of photodiodes used as photosensors requires a determination of the number of electron-hole pairs produced by scintillation light. One method involves comparing signals produced by X-ray absorptions occurring directly in the avalanche photodiode with the light signals. When the light is derived from light-emitting diodes in the 400-600 nm range, significant non-linear behaviour is reported. In the present work, we extend the study of the linear behaviour to large-area avalanche photodiodes, of Advanced Photonix, used as photosensors of the vacuum ultraviolet (VUV) scintillation light produced by argon (128 nm) and xenon (173 nm). We observed greater non-linearities in the avalanche photodiodes for the VUV scintillation light than reported previously for visible light, but considerably less than the non-linearities observed in other commercially available avalanche photodiodes. r 2002 Published by Elsevier Science B.V.

Detection of VUV photons with large-area avalanche photodiodes

“…Non-linear effects are less than 2, 4, and 10% for gains below 50, 100, and 240, respectively. They are higher than those obtained for 172-nm photons and for visible light [4,20]. Nevertheless, the non-linearities observed in this type of photodiode are smaller than those observed with other APD types [4].…”

“…Different studies have proved that the LAAPD response characteristics for VUV are different from those for visible light, used to determine most of the characteristics of the photodiodes [20][21][22]. The X-ray-to-photon detection nonlinearity, the sensitivity to magnetic fields and the relative variation of gain with temperature have been measured for VUV, presenting higher values when compared to visiblelight detection.…”

“…These LAAPDs can replace PMTs or CsI-based photosensors in applications where the light level allows the use of low-gain photosensors [11,12,[16][17][18][19]. For example, the detection of primary and secondary scintillation in rare gases is not only used in gas scintillation X-ray detectors [11,12], but also in many other types of radiation detectors, which have been investigated recently [16][17][18][19].Different studies have proved that the LAAPD response characteristics for VUV are different from those for visible light, used to determine most of the characteristics of the photodiodes [20][21][22]. The X-ray-to-photon detection nonlinearity, the sensitivity to magnetic fields and the relative variation of gain with temperature have been measured for VUV, presenting higher values when compared to visiblelight detection.…”

“…Non-linearities have been reported at high current densities and attributed to space-charge effects, reduced local electric fields, and heating in the avalanche region that occur for X-ray interactions at high gains [4,20]. While charge carriers produced by X-rays are concentrated in a very small volume of the APD, within a few microns, for light measurements they are produced within a much larger region.…”

Detection of VUV Light with Avalanche Photodiodes

“…For the 128 and 172 nm VUV light from argon and xenon scintillation, the effective quantum efficiency, here defined as the average number of free electrons produced in the APD per incident VUV photon is 0.5 and 1.1, respectively, corresponding to a spectral sensitivity of about 50 and 150 mA/W [4,19]. In this chapter, we review and summarize the results of our investigation, namely the gain non-linearity between the detection of X-rays and VUV light [20], the gain dependence on temperature [21,22], the behaviour under intense magnetic fields [23], the minimum detection limit, i.e. the minimum number of photons detectable above the noise level, and the statistical fluctuations in VUV photon detection [24].…”