Development of a multi-pixel photon sensor with single-photon sensitivity

Abstract

A multi-pixel photon sensor with single-photon sensitivity has been developed. Based on a hybrid photo-detector (HPD) technology, it consists of a photocathode and a multi-pixel avalanche diode (MP-AD). The developed HPD has a proximity-focused structure, where the photocathode and MP-AD face each other with a small gap of 2.5 mm. The MP-AD, which has an effective area of 16mm×16mm, is composed of 8×8 pixel and has been specially designed for the HPD. The maximum gain of the HPD is 5×10 4 , sufficiently high to detect single photons with a timing resolution better than 100 ps. Up to four photoelectrons can be clearly identified as distinct peaks in a pulse-height spectrum, thanks to the low noise characteristics of the HPD. It is also 1 demonstrated that the HPD can be operated with good performance in a magnetic field as high as 1.5T.

Development of a multipixel hybrid photodetector with high quantum efficiency and gain

“…The previous study [7] suggests that p+ layer at the entrance forms a dead layer and the energy deposited there does not contribute to the electron-bombarded gain. Since the fluctuation of deposited energy in the dead layer predetermines the overall energy resolution, the thinnest possible dead layer is desirable.…”

“…The maximum reachable avalanche gains of these MP-ADs are limited by the breakdown voltage of the worst pixel contained. Without a bad pixel, the avalanche gain reaches 100, as shown in [7].…”

“…Since the fluctuation of deposited energy in the dead layer predetermines the overall energy resolution, the thinnest possible dead layer is desirable. In this study, a thinner dead layer than before [6] is realized by low energy implantation of a p-type impurity, boron.…”

“…Such photon sensors can be realized with hybrid photo-detector (HPD) technology consisting of a photocathode and a multi-pixel avalanche diode (MP-AD). We succeeded in building an HPD having 8x8 pixels so far [6], [7], with a gain as high as 5x10 4 , sufficient to detect a single photon with a timing resolution of better than 100 ps. Operation in a magnetic field up to 1.5 T was confirmed as well.…”

“…In previous studies [6], one of the important suggestions is that the dead layer at the entrance of the MP-AD plays a crucial role for the energy resolution. We now demonstrate improved performance of the HPD with a new MP-AD having a thinner dead layer compared to the one (old MP-AD) developed in the previous study.…”