127,980 research outputs found
Hybrid photon detectors
Hybrid photon detectors detect light via vacuum photocathodes and accelerate the emitted photoelectrons by an electric field towards inversely polarized silicon anodes, where they are absorbed, thus producing electron-hole pairs. These, in turn, are collected and generate electronic signals on their ohmic contacts. This review first describes the characteristic properties of the main components of hybrid photon detectors: light entrance windows, photocathodes, and silicon anodes. Then, essential relations describing the trajectories of photoelectrons in electric and magnetic fields and their backscattering from the silicon anodes are derived. Depending on their anode configurations, three families of hybrid photon detectors are presented: hybrid photomultiplier tubes with single anodes for photon counting with high sensitivity and for gamma spectroscopy; multi-anode photon detector tubes with anodes subdivided into square or hexagonal pads for position-sensitive photon detection; imaging silicon pixel array tubes with finely segmented anodes for photon-sensitive imaging devices. Some of the hybrid photon detectors’ applications and achievements in radiation detection are discussed and compared with competing devices such as photomultipliers, image intensifiers, photodiodes, silicon drift chambers, charge coupled devices, visible light photon counters, and photographic emulsions
Application of electron multiplying CCD technology in space instrumentation
Electron multiplying CCD (EMCCD) technology has found important initial applications in low light surveillance and photon starved scientific instrumentation. This paper discusses the attributes of the EMCCD which make it useful for certain space instruments, particularly those which are photon starved, and explores likely risks from the radiation expected in such instruments
Charge Offset Stability in Si Single Electron Devices with Al Gates
We report on the charge offset drift (time stability) in Si single electron
devices (SEDs) defined with aluminum (Al) gates. The size of the charge offset
drift (0.15 ) is intermediate between that of Al/AlO/Al tunnel junctions
(greater than 1 ) and Si SEDs defined with Si gates (0.01 ). This range
of values suggests that defects in the AlO are the main cause of the charge
offset drift instability
Superinjection of holes in homojunction diodes based on wide-bandgap semiconductors
Electrically driven light sources are essential in a wide range of
applications, from indication and display technologies to high-speed data
communication and quantum information processing. Wide-bandgap semiconductors
promise to advance solid-state lighting by delivering novel light sources.
However, electrical pumping of these devices is still a challenging problem.
Many wide-bandgap semiconductor materials, such as SiC, GaN, AlN, ZnS, and
Ga2O3, can be easily doped n-type, but their efficient p-type doping is
extremely difficult. The lack of holes due to the high activation energy of
acceptors greatly limits the performance and practical applicability of
wide-bandgap semiconductor devices. Here, we study a novel effect which allows
homojunction semiconductors devices, such as p-i-n diodes, to operate well
above the limit imposed by doping of the p-type material. Using a rigorous
numerical approach, we show that the density of injected holes can exceed the
density of holes in the p-type injection layer by up to three orders of
magnitude, which gives the possibility to significantly overcome the doping
problem. We present a clear physical explanation of this unexpected feature of
wide-bandgap semiconductor p-i-n diodes and closely examine it in 4H-SiC,
3C-SiC, AlN and ZnS structures. The predicted effect can be exploited to
develop bright light emitting devices, especially electrically driven
non-classical light sources based on color centers in SiC, AlN, ZnO and other
wide-bandgap semiconductors.Comment: 6 figure
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