At&t Bell Laboratories

Lucent Technologies Inc.

At+t Corp.

Neil E Hunt

Erdmann F Schubert

George J Zydzik

John Milo Poate

Matthias Passlack

Yiu-Huen Wong

Alastair M Glass

Leonard C Feldman

Niloy K Dutta

Dale C Jacobson

Russell J Fischer

Arjen M Vredenberg

An optoelectronic lII-V or II-VI semiconductor device comprises a thin film coating with optical characteristics providing low midgap interface state density. A field effect device for inversion channel applications on III-V semiconductors also comprises a thin dielectric film providing required interface characteristics. The thin film is also applicable to passivation of states on exposed surfaces of electronic III-V devices. The thin film comprises a uniform, homogeneous, dense, stoichiometric gallium oxide (Ga.sub.2 O.sub.3) dielectric thin film, fabricated by electron-beam evaporation of a single crystal, high purity Gd.sub.3 Ga.sub.5 O.sub.12 complex compound on semiconductor substrates kept at temperatures ranging from 40.degree. to 370.degree. C. and at background pressures at or above 1.times.10.sup.-10 Torr.

Gallium oxide coatings for optoelectronic devices using electron beam

Disclosed is a method of fabricating a stoichiometric gallium oxide (Ga.sub.2 O.sub.3) thin film with dielectric properties on at least a portion of a semiconducting, insulating or metallic substrate. The method comprises electron-beam evaporation of single crystal, high purity Gd.sub.3 Ga.sub.5 O.sub.12 complex compound combining relatively ionic oxide, such as Gd.sub.2 O.sub.3, with the more covalent oxide Ga.sub.2 O.sub.3 such as to deposit a uniform, homogeneous, dense Ga.sub.2 O.sub.3 thin film with dielectric properties on a variety of said substrates, the semiconducting substrates including III-V and II-VI compound semiconductors.

Electron beam deposition of gallium oxide thin films using a single high

Absorption properties of an optically active medium can be changed drastically by a Fabry-Perot microcavity. Optically active medium of the cavity includes a host material which is not optically active and at least one rare earth ion which provides optical activity to the medium. The Fabry-Perot cavity is designed to be resonant with excitation wavelength of an absorption band of the host material. The excitation is provided by a source of radiation positioned such that the radiation impinges on the cavity at an angle within a range of from zero to less than 90 degrees from the normal to the top surface of the cavity. In one embodiment Er-implanted SiO.sub.2 is used as the optically active medium. SiO.sub.2 :Er has an absorption band at 980 nm and an emission band at 1.55 .mu.m due to 4f intra-atomic transitions of Er.sup.3+ ions. The Fabry-Perot cavity is designed to be resonant with the 980 nm absorption band of SiO.sub.2 :Er. The efficiency of the cavity structure is much higher as compared to a no-cavity structure, while the spectral features of the active SiO.sub.2 :Er emission are unaltered. The structure can be used for optically pumped semiconductor devices, such as optical amplifiers or lasers, which could be operated with a higher overall efficiency.

Absorption resonant rare earth-doped micro-cavities

This invention embodies single mirror light-emitting diodes (LEDs) with enhanced intensity. The LEDs are Group III-V and/or II-IV compound semiconductor structures with a single metallic mirror. The enhanced intensity is obtained by placing an active region of the LED having from two to ten, preferably from four to eight, quantum wells at an anti-node of the optical node of the device created by a nearby metallic mirror. Such multiquantum well LED structures exhibit enhanced efficiencies approaching that of a perfect isotropic emitter.

Single mirror light-emitting diodes with enhanced intensity

Described is a resonant-cavity p-i-n photodetector based on the reflection or transmission through a Fabry-Perot cavity incorporating non-epitaxial, amorphous layers with alternating refractive index difference which layers are electron-beam deposited on a light-gathering side of a commercially available photodetector. The materials of the Fabry-Perot cavity are selectable from materials, refractive indices of which fall within a large range (from n=1.26 for CaF.sub.2 to n=3.5 for Si) preferably from materials which are depositable in an amorphous state. The material combinations are selected so that only wavelengths resonant with the cavity mode will be detected. The microcavity of the RC-PIN design can also be deposited on any existing detector structure, without modification of semiconductor growth. Such a photodetector would be useful for wavelength de-multiplexing applications. The ease of layer deposition, as well as the high degree of tailorability of spectral position, spectral detection width, and maximum numerical aperture of efficient detection, make the RC-PIN attractive for use in wavelength demultiplexing applications. An exemplary RC-PIN photodetector includes a Si/SiO.sub.2 Fabry-Perot cavity electron-beam deposited on the InP substrate of a commercial InGaAs photodetector. The detection efficiency relative to a reference device was 52 percent at the resonant wavelength of 1350 nm, with a resonance width of 14 nm, and a 4 percent response for off-resonance wavelengths in the 1100-1700 nm range.

Photodetector with a resonant cavity

This invention embodies an optical device with a Fabry-Perot cavity formed by two reflective mirrors and an active layer which is doped with a rare earth element selected from lanthanide series elements with number 57 through 71. The thickness of the active layer being a whole number multiple of .lambda./2 wherein .lambda. is the operating, or emissive, wavelength of the device, said whole number being one of the numbers ranging from 1 to 5, the fundamental mode of the cavity being in resonance with the emission wavelength of said selected rare earth element. Cavity-quality factors exceeding Q=300 and finesses of 73 are achieved with structures consisting of two Si/SiO.sub.2 distributed Bragg reflector (DBR) mirrors and an Er-implanted (.lambda./2) SiO.sub.2 active region. The bottom DBR mirror consists of four pairs and the upper DBR mirror consists of two-and-a half pairs of quarterwave (.lambda./4) layers of Si and SiO.sub.2. Photoluminescence at room temperature reveals a drastic enhancement of the luminescence intensity of the cavity emitted along the optical axis of the cavity versus the luminescence without the top mirror. The luminescence intensity of the cavity is typically 1-2 orders of magnitudes higher as compared to structures without a cavity. Furthermore, since the emission wavelength and the intensity decrease for off-normal emission angles, the change in emission wavelength can be quantitatively described by assuming that the on-axis component of the optical wave is resonant with the cavity.

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Scotch Plains, NJ, United States of America

Neil E Hunt