Development of a novel, windowless, amorphous selenium based photodetector for use in liquid noble detectors

Abstract

Detection of the vacuum ultraviolet (VUV) scintillation light produced by liquid noble elements is a central challenge in order to fully exploit the available timing, topological, and calorimetric information in detectors leveraging these media. In this paper, we characterize a novel, windowless amorphous selenium based photodetector with direct sensitivity to VUV light. We present here the manufacturing and experimental setup used to operate this detector at low transport electric fields (2.7–5.2 V/μm) and across a wide range of temperatures (77 K–290 K). This work shows that the first proof-of-principle windowless amorphous selenium device is robust under cryogenic conditions, responsive to VUV light at cryogenic temperatures, and preserves argon purity. These findings motivate a continued exploration of amorphous selenium devices for simultaneous detection of scintillation light and ionization charge in noble element detectors.

Non-Markovian Hole Excess Noise in Avalanche Amorphous Selenium Thin Films

“… 25 Moreover, it can be uniformly deposited near room-temperature over larger areas as compared to crystalline semiconductors and is compatible with readout electronics. 37 , 38 At high electric fields, hole transport in a -Se can be shifted entirely from localized to extended states, resulting in a single carrier hole impact ionization avalanche with prior reports of ENF ∼ 1, corresponding to a gain of ∼1000, as shown in Figure 1 a, 23 indicating the existence of a peculiar noise reduction mechanism in the hole avalanche process in a -Se. Thus, modeling the extended states transport of “hot” holes involved in the single carrier impact ionization phenomenon is pivotal to the understanding of the nature of avalanche gain and excess noise in a -Se-based detectors.…”

“…Ultralow thermal generation rates combined with a single carrier hole avalanche process renders a -Se to be either used as a short visible light absorbing APD responsive in the spectrum window of 400–450 nm where a -Se demonstrates an external quantum efficiency ∼90% ,− or coupled to existing photon absorbing layers just to be used as an efficient hole transport layer (HTL) with avalanche capabilities, thus encompassing photonic applications across the visible electromagnetic spectrum, see Figure b . Moreover, it can be uniformly deposited near room-temperature over larger areas as compared to crystalline semiconductors and is compatible with readout electronics. , At high electric fields, hole transport in a -Se can be shifted entirely from localized to extended states, resulting in a single carrier hole impact ionization avalanche with prior reports of ENF ∼ 1, corresponding to a gain of ∼1000, as shown in Figure a, indicating the existence of a peculiar noise reduction mechanism in the hole avalanche process in a -Se. Thus, modeling the extended states transport of “hot” holes involved in the single carrier impact ionization phenomenon is pivotal to the understanding of the nature of avalanche gain and excess noise in a -Se-based detectors. − …”