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Optical Engineering

Theoretical study of potential ultralow noise, confined state photodetectors
Author(s): Yang Wang; Nabil S. Mansour; Ali F. Salem; Kevin F. Brennan; P. Paul Ruden
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Paper Abstract

A review of the basic issues implicit in the design of confined state photodetectors is presented. The basic device structure of a confined state photomultiplier consists of repeated unit cells each comprised of a narrow-gap semiconductor layer sandwiched between barrier layers of wider band-gap material. Gain in these structures is derived through carrier multiplication via impact excitation of confined electrons out of the narrow-gap semiconductor layer. Different device designs are considered in an attempt to maximize the device gain at minimum dark current. In some implementations, the barrier layers are chosen to be graded such that the leading edge discontinuity is at least twice that at the trailing edge of the well forming an asymmetric well design. We find that an asymmetric well design offers a much higher impact excitation of electrons confined within the well at a lower operating voltage than a symmetric well design, however, at the expense of increased dark current. Quantum versus classical confinement of the electrons within the well is also investigated. Though the ionization rate within the classical confinement design is less under comparable conditions to that in the quantum confinement design, the dark current is much less within the classical structure than in the quantum structure, giving a higher excitation-rate-to-dark-current ratio. The gain and dark current are investigated in structures made from GaN/AlGaN, HgTe/HgCdTe, and GaAs/AlGaAs.

Paper Details

Date Published: 1 April 1994
PDF: 9 pages
Opt. Eng. 33(4) doi: 10.1117/12.163192
Published in: Optical Engineering Volume 33, Issue 4
Show Author Affiliations
Yang Wang, Georgia Institute of Technology (United States)
Nabil S. Mansour, Georgia Institute of Technology (United States)
Ali F. Salem, Georgia Institute of Technology (United States)
Kevin F. Brennan, Georgia Institute of Technology (United States)
P. Paul Ruden, Univ. of Minnesota/Twin Cities (United States)


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