title: Electroded avalanche amorphous selenium (a-Se) photosensor.
abstract: Although avalanche amorphous selenium (a-Se) is a very promising photoconductor for a variety of imaging applications, it is currently restricted to applications with electron beam readout in vacuum pick-up tube called a High-gain Avalanche Rushing Photoconductor (HARP). The electron beam readout is compatible with high definition television (HDTV) applications, but for use in solid-state medical imaging devices it should be replaced by an electronic readout with a two-dimensional array of metal pixel electrodes. However, due to the high electric field required for avalanche multiplication, it is a technological challenge to avoid possible dielectric breakdown at the edges, where electric field experiences local enhancement. It has been shown recently that this problem can be overcome by the use of a Resistive Interface Layer (RIL) deposited between a-Se and the metal electrode, however, at that time, at a sacrifice in transport properties.Here we show that optimization of RIL deposition technique allows for electroded avalanche a-Se with transport properties and time performance previously not achievable with any other a-Se structures. We have demonstrated this by detailed analysis of transport properties performed by Time-of-Flight (TOF) technique. Our results showed that a stable gain of 200 is reached at 104 V/μm for a 15-μm thick a-Se layer, which is the maximum theoretical gain for this thickness. We conclude that RIL is an enabling technology for practical implementation of solid-state avalanche a-Se image sensors.
authors.affiliation: Physics Department, Lakehead University, Thunder Bay, Ontario, Canada ;  Thunder Bay Regional Research Institute, Thunder Bay, Ontario, Canada.
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Bubon
authors.forename: Giovanni
authors.initials: G
authors.lastname: Decrescenzo
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: Yuji
authors.initials: Y
authors.lastname: Ohkawa
authors.forename: Kazunori
authors.initials: K
authors.lastname: Miyakawa
authors.forename: Tomoki
authors.initials: T
authors.lastname: Matsubara
authors.forename: Kenji
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Kenkichi
authors.initials: K
authors.lastname: Tanioka
authors.forename: Misao
authors.initials: M
authors.lastname: Kubota
authors.forename: John A
authors.initials: JA
authors.lastname: Rowlands
authors.forename: Alla
authors.initials: A
authors.lastname: Reznik