Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is – Heterojunction
Reexamination Certificate
2000-07-27
2001-12-11
Bowers, Charles (Department: 2813)
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
Heterojunction
C438S046000, C438S056000, C438S057000
Reexamination Certificate
active
06329668
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to intersubband photoconductive detectors, and more particularly to detectors prepared from n-type InGaAs quantum dots in a InGaP matrix.
BACKGROUND OF THE INVENTION
The importance of semiconductor emitters and detectors is rapidly increasing along with progress in the opto-electronic field, such as optical fiber communication, optical data processing, storage and solid state laser pumping.
Quantum dots formed by the Stranski-Krastanow growth mode which is obtained as deposit of the highly strained material on a substrate is promising for developing zero dimensional quantum devices for light emitting sources and detectors.
Quantum dot infrared photodetectors are one of the promising applications for semiconductor devices based on zero dimensional quantum structures. There is an increasing need for sources and detectors for mid and far infrared spectral regions due to the broad range of the applications such as IR spectroscopy of chemical analysis, remote sensing, and atmospheric communications. Similar to the case of quantum well intersubband photodetectors (QWIPs), quantum dots are expected to play an important role in infrared photodetectors. Compared to QWIPs, quantum dot detectors have advantages such as a slowing of the intersubband relaxation time due to reduced electron-phonon interaction. In addition, unlike a quantum well, quantum dots are sensitive to normally incident photons due to the breaking of the polarization selection rules.
Recently, long wavelength infrared (LWIR) intersubband absorption in the range of 60 meV~120 meV from InAs/(Al)GaAs, normal incidence LWIR intersubband absorption around 88 meV from InGaAs/GaAs, and LWIR intersubband absorption around 150 meV from n-doped InAs/GaAs quantum dots have been reported. Also mid-infrared photoconductivity in InAs/AlGaAs at near 3 &PHgr;m has been observed.
SUMMARY OF THE INVENTION
An object, therefore, of the invention is a quantum dot intersubband infrared photodetector.
A further object of the subject invention is an photodetector having an active region formed of multiple stacks of aluminum free InGaAs/InGaP quantum dots.
A still further object of the subject invention is an investigation of the optimized growth condition for controlling size of the quantum dots by LP-MOCVD.
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In situ fabrication of self-aligned InGaAs quantum dots on GaAs multiatomic steps by metalorganic chemical vapor deposition, M. Kitamura et al., Appl. Phys. Lett. Jun. 1995, vol. 66, No. 26, pp. 3663-3665.
Selective formation of one- and two-dimensional arrayed InGaAs quantum dots using Ga2O3 thin film as a mask material, Cheol Koo Hahn et al., Appl. Phys. Lett., Oct. 1998, vol. 73, No. 17, pp. 2379-2481.
Bowers Charles
MP Technologies L.L.C.
Thompson Craig
Welsh & Katz Ltd.
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