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US 4,727,349 AGranted
Depleted channel photoconductor
AssigneeCanadian Patents and Development Limited
InventorsRobert I. MacDonald, Dennis K. W. Lam, Julian P. Noad
Life of this patent
Estimating the term…
Abstract
Photoconductors with channels that lie in the surface depleted region of a GaAs structure are described. These devices have nanoampere bias current, and exhibit photoconductive gain. In contrast to other photoconductors, their low frequency responsivity is of the same order as that in the GHz region, alleviating problems of equalization necessary in receiver applications. As well, these devices exhibit over 60 dB isolation as optoelectronic switches.
Claims11
A photoconductive device, comprising:
- a substrate made of a material selected from a group consisting of electrically semi-insulating and insulating substances;
- a channel layer on the substrate, the said channel layer being made of a semiconductive material selected from a group consisting of undoped, low doped and compensated semi-conductive substances;
- and
- a pair of mutually separated metal contact electrodes on the channel layer;
- the said channel layer being thin enough that the depletion region created therein between the electrodes penetrates into the said substrate,
- so that
- photons impinging upon the channel layer generate a photocurrent therein between the said electrodes.
4 more elements
A photoconductive device, comprising:
- a undoped semi-insulating or insulating substrate;
- a channel layer on the substrate, the said channel layer being on the order of 1-2 .mu.m thick and made of undoped GaAs having the dopant concentration of less than 5.times.10.sup.-14 cm.sup.-3 ;
- a pair of mutually separated Ni-Ge-Au metal contact electrodes;
- and
- an n.sup.+ cap layer provided between the channel layer and the pair of the contact electrodes, the said cap layer being on the order of 0.25 .mu.m thick and having the dopant concentration of more than 10.sup.18 cm.sup.-3 ;
- so that
- photons impinging upon the channel layer generate a photocurrent between the said contact electrodes.
4 more elements
Dependencies are inferred from the claim text.