Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Charge transfer device
Reexamination Certificate
1999-02-05
2001-12-04
Abraham, Fetsum (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Charge transfer device
C257S078000, C257S081000, C257S186000, C257S189000, C257S201000
Reexamination Certificate
active
06326654
ABSTRACT:
BACKGROUND OF THE INVENTION
A number of applications of ultraviolet photodetectors require devices having both high responsivity and relatively high speed. Such applications include, for example, ultraviolet energy-based optical communication systems and missile warning systems, a list which is considered exemplary but not limiting. The periodic table group III-Nitride alloy, Al
x
Ga
1−x
N, is a promising material for fabricating such ultraviolet photodetectors partly because of its direct bandgap, which spans the range of 3.4 electron volts for GaN to 6.1 electron volts for AlN. (Such properties are described, for example, in S. Strite and H. Morkoc, “GaN, AlN, and InN: A Review”, J. Vac. Sci. Technol. B10, 1237, 1992.) Hence, in view of the direct relationship between bandgap and cut-off wavelength, as is known in the art, photodetectors based on an appropriate choice of III-Nitride alloy composition may provide ultraviolet responses in the wavelength range below a wavelength residing somewhere between 365 nanometers and 200 nanometers, i.e., provide photodetectors of cut-off wavelengths in the range of 200 nanometers to 365 nanometers. These III-Nitride alloys have been useful in the fabrication of ultraviolet light-emitting devices having output in the same spectral range.
The good rejection of long wavelength light thus provided in a III-Nitride ultraviolet detector is additionally desirable for applications exposing the detector to background sunlight “noise”. Sunlight, even on the earth's surface, has a strong ultraviolet spectral component in the wavelength range greater than about 300 nanometers in addition to well known visible and infrared components. Ultraviolet photodetectors that do not respond to light of wavelength longer than about 300 nanometers may therefore be referred to as “solar blind” ultraviolet detectors. Photoconductors and phototransistors fabricated from aluminum gallium nitride (Al
x
Ga
1−x
N) are therefore deemed good candidates for high responsivity, solar blind detectors. The signal gain of some possible detector configurations of this material, such as photoconductor and phototransistor devices, however, is achieved at the expense of device operating speed. Photoconductors in particular have shown extremely long recovery times—as is disclosed in M. Razeghi and A. Rogalski, “Semiconductor UV Detectors”, J. Appl. Phys. 79, 7433, 1996 and in B. Goldenberg, J. D. Zook and R. J. Ulmer, “Fabrication and Performance of GaN Detectors”, Proc. of the Topical Workshop on III-V Nitrides, Nagoya, Japan, 1995.[2,3].
In contrast with such photoconductors and phototransistors, III-Nitride photodiodes are capable of high speed operation; see, for example, J. M. Van Hove, R. Hickman, J. J. Klaassen, P. P. Chow, and P. P. Ruden, “Ultraviolet-Sensitive, Visible-Blind GaN Photodiodes Fabricated by Molecular Beam Epitaxy”, Appl. Phys. Lett. 70, 2282, 1997; and S. Krishnankutty, W. Yang, T. Nohava and P. P. Ruden, “Fabrication and Characterization of GaN/AlGaN UV Band Heterojunction Photodiodes”, MRS Nitride Internet Journal, Volume 3, Article 7, 1998. Unfortunately, however, photodiode responsivity, as is disclosed in these same publications, is rather low in view of there being no signal gain mechanism operating in a conventional photodiode. The present invention provides improvement in this gain aspect of a photodiode and makes the III-Nitride photodiode a viable tool for wide bandwidth, solar blind, photodetection.
SUMMARY OF THE INVENTION
The present invention provides a semiconductor ultraviolet photon detector wherein signal detection and signal amplification occur in charge conductor-coupled separate material portions of the device, a detector also affording desirable spectral selectivity and response speed characteristics.
It is an object of the present invention therefore to provide a hybrid ultraviolet detector combining the photon-charge carrier conversion capability of one semiconductor material with the charge carrier multiplication capability of a second semiconductor material.
It is another object of the invention to provide a semiconductor ultraviolet detector of improved response speed in comparison with conventional ultraviolet detectors.
It is another object of the invention to provide an ultraviolet detector having a desirable optical signal to noise ratio.
It is another object of the invention to provide an ultraviolet detector having a desirable optical signal to noise ratio afforded by way of shielding optical noise signal components from susceptible detector areas.
It is another object of the invention to provide an ultraviolet detector combining desirable properties of direct bandgap and indirect bandgap semiconductor materials in a common structure.
It is another object of the invention to provide an ultraviolet detector having desirable input optical signal spectral selectivity characteristics.
It is another object of the invention to provide an ultraviolet detector using the avalanche charge carrier multiplication phenomenon.
It is another object of the invention to provide an ultraviolet detector using nitride materials.
It is another object of the invention to provide an ultraviolet detector using periodic table group III materials.
It is another object of the invention to provide an ultraviolet detector combining the benefits of III-Nitride and silicon materials.
It is another object of the invention to provide an ultraviolet detector combining the mechanism of charge carrier diffusion with charge carrier avalanche multiplication.
It is another object of the invention to provide an ultraviolet detector combining the benefits of laterally diffusing charge carriers with vertically oriented charge carrier multiplication.
It is another object of the invention to provide an ultraviolet detector in which charge carrier recombination effects are suppressed by an included charge carrier diffusion structure.
It is another object of the invention to provide an ultraviolet detector in which efficient diffused charge carrier injection into a charge carrier multiplication region is achieved.
Additional objects and features of the invention will be understood from the following description and claims and the accompanying drawings.
These and other objects of the invention are achieved by a group III-Nitride, solar blind, ultraviolet photodetector apparatus comprising the combination of:
a laterally-elongated group III-Nitride first semiconductor material layer structure;
an optically exposed radiant energy reception surface region located at a first lateral extremity of said first semiconductor material layer structure;
an optically obscured second semiconductor material layer structure charge carrier avalanche multiplication region vertically disposed in a downstream charge carrier location at a second lateral extremity on a surface of said first semiconductor material layer structure;
first and second charge carrier collection metallic electrode members received on a layer of said avalanche multiplication region at said second lateral extremity and on a surface of said first semiconductor material layer structure respectively.
REFERENCES:
patent: 4383267 (1983-05-01), Webb
patent: 5146465 (1992-09-01), Khan et al.
patent: 5192861 (1993-03-01), Breskin et al.
patent: 5192987 (1993-03-01), Khan et al.
patent: 5198673 (1993-03-01), Rougeot et al.
patent: 5239188 (1993-08-01), Takeuchi et al.
patent: 5278435 (1994-01-01), Van Hove et al.
patent: 5294789 (1994-03-01), Kruger
patent: 5311010 (1994-05-01), Kruger
patent: 5378960 (1995-01-01), Tasker et al.
patent: 5389571 (1995-02-01), Takeuchi et al.
patent: 5393993 (1995-02-01), Edmond et al.
patent: 5523589 (1996-06-01), Edmond et al.
patent: 5596186 (1997-01-01), Kobayashi
patent: 5602418 (1997-02-01), Imai et al.
patent: 5621227 (1997-04-01), Joshi
patent: 5625202 (1997-04-01), Chai
patent: 5677538 (1997-10-01), Moustakas et al.
patent: 5679965 (1997-10-01), Schetzina
patent: 5686721 (1997-11-01), Schmidt-Bocking
patent: 5686734 (1997-11-01), Hamakawa et al.
patent: 568
Krishnankutty Subash
Ruden P. Paul
Abraham Fetsum
Hollins Gerald B.
Kundert Thomas L.
The United States of America as represented by the Secretary of
LandOfFree
Hybrid ultraviolet detector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hybrid ultraviolet detector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hybrid ultraviolet detector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2560627