Electronics and Telecommunications Research Institute

Bun Lee

Jong-Hyeob Baek

Sung-Woo Choi

Jin-Hong Lee

Jong Hyeob Baek

Mee-Young Yoon

Yong-gyu Choi

Dug-Bong Kim

Jong-bae Kim

Doo-hee Cho

Jong Hyub Baek

Sahng-gi Park

Kyong-hon Kim

A method for forming two conductive films isolated electrically from each other on the surface of a fiber is provided. According to the method, a fiber is attached into the grooves on a silicon substrate using photoresist as glue. A photoresist pattern for a conductive film on the surface of the fiber is formed by a photolithography process. After wet-etching some amount of the fiber on the patterned area, which is needed for lifting off a metal film deposited on the unnecessary area, a metal film is deposited over whole area of the wafer. Removing photo-resist by a heated stripper solution leaves a metal film only on the patterned area of the fiber and detaches the fibers from the grooves of the wafer The second metal film on the other side of the fiber can be formed by the same procedures as the first metal film except that the deposited surface of the fiber must be attached to the grooves upside down. The poled fiber using two conductive films can be applied to manufacture elements used in opto-electronic and fiber communication devices such as a modulator, a tunable filter and a switch, an electric field sensor, and a nonlinear fiber optics device such as a frequency converter, a dispersion compensator.

Method for forming two thin conductive films isolated electrically from each other on a fiber

The method of manufacturing VCSEL composed of multiple material layers uses a main measuring laser having same wavelength of that of VCSEL so as to estimate the growth periods required for growing a predetermined thickness of the material layers by analyzing the reflected signal of the main measuring laser and then control the growth time durations of subsequent material layers. This method eliminates the need of pre-knowledge of refractive indexes and the growing speeds of the material layers. Also, an interruptive process for measuring thickness, growth speed or refractive indexes can be omitted so as to perform the entire epitaxial growth in-situ and thus improve the reproducibility and the uniformity. In addition, a subsidiary measuring laser may be used other than the main measuring laser for improving the accuracy of the control of growth time duration, where the subsidiary measuring laser has a different wavelength from that of VCSEL. The subsidiary measuring laser may be used especially in the case of fabricating the VCSEL without any buffer layer.

Real time epitaxial growth of vertical cavity surface-emitting laser using a reflectometry

A method for sensing the etch of distributed Bragg reflector (called DBR below) in a real time is provided. More particularly, a method for searching informations of etch speed and etch stop step by monitoring the etching procedure in the wet etching method which is a post-process in the semiconductor device manufacturing process. A laser beam is irradiated on the sample sunk in the etching solution during the etching process is on the way. Then, computer measures the intensity of laser beam reflected on the sample, analyzes the periodic signals occurred by its interference and obtains the etching speed of the sample in a real time. The laser provides thermal energy on the sample during wet etching and occurs irregular etching speed on a beam contacting part of sample and non contacting part. Uniform etching speed can be obtained in the entire sample using a convex lens having a suitable focal distance.

Method for sensing etch of distributed bragg reflector in real time

The present invention is related to a surface transmission-type optical switch of the 1-D array method, and more particularly to a surface transmission-type optical switch, which is manufactured by Fabry-perot type not to need optical waveguides and integrated only by amplifiers of the space division multiplex. A surface transmission-type optical switch according to the present invention is a structure to overlap 3 optical amplifiers for optical switching, and an incoming signal beam is amplified through the first optical amplifier and becomes an n&times;n amplifiers of a matrix type with the second signal amplification, passing through the second optical amplifier overlapped on the first amplifier. Amplified signal beams through 2 amplifiers perform n&times;n matrix switching through the third amplifier, and go out to the opposite side of the incoming surface. Characteristics of a surface-type Fabry perot type structure is that selective amplification is possible, by selecting only one wavelength in multiple wavelengths as the gain bandwidth is 5 nm or less.

Optical switch of surface transmission type by one-dimensional array method

A method for making a surface-type semiconductor laser specially devised to keep the stability of the wavelength at the next generation laser for WDM, which does not cause a raising characteristic variation with time because the laser wavelength of the individual device can be controlled easily and exactly as required and the devices in which the wavelength control have completed is stable in their material properties. The surface-type semiconductor laser is made by growing the cladding layer within the active layer at a low temperature, growing the upper and the underlying superlattice mirror layers and the quantum well structure within the active layer at a high temperature and then sintering the structure thus formed at a high temperature.

Method for manufacturing tunable laser

The present invention relates to a method for growing new binary, ternary and quaternary epitaxial layers of III-V compound semiconductors which have the characteristics of low temperature growth, good stability and high-purity, using remote plasma, comprising the steps of converting H.sub.2 and He mixed gas into a plasma state; heating a high-purity of solid source to generate a vaporized source; reacting the vaporized source with H.sub.2 under the H.sub.2 and He plasma environment to produce V-hydrides in situ; introducing the V-hydrides directly into group III source without passing through the plasma; and reacting V-hydrides with group III source on a substrate to form an epitaxial thin layer of III-V compound semiconductors. According to the present invention, high-purity of epitaxial thin layer can be formed at a low temperature, an economical process that does not require an ultrahigh vacuum, a stabilized process that does not need to handle poisonous gas for the reaction with gropu V, and a simple process for manufacturing the various binary, ternary and quaternary compound semiconductor alloys can be provided. Thus, the method of the present invention can be applied to the future information and communication industry, for example, high speed, high frequency optical communication system with (Ga, In, Al)--(As, P, Sb) based on III-V compound semiconductor electronic and optical devices, and the circuitry thereof including heterojunction bipolar transistors, high electron mobility transistors, semiconductor lasers and optical switches.

Method for growing epitaxial layers of III-V compound semiconductors

An improved surface-emitting laser device by which the light emitting wave length can be easily varied since the electric potential grown using the thin film material having a desired lattice rate uses a very small portion of activation layers, and by which the continuous oscillation is made at room temperature by using the reflector having high reflective index. Thus, optical characteristics are increased, which includes a GaAs substrate; a lower reflector is formed of multiple layers of AlAs/GaAs heterogenous thin films having a reflective index of 1 on the GaAs substrate; a tooth-shaped grading layer is formed of a lower reflector on the lower reflector and an In.sub.x Ga.sub.1-x As thin film having a large lattice rate in a compositional grading method; a tooth-shaped InGaAs grading well is formed on the In.sub.x Ga.sub.1-x As grading layer as an In composition of which reduced rather than the grading layer; a buffer layer is formed on the In.sub.x Ga.sub.1-x As thin film and formed of a lattice-bonded InP; and an upper semiconductor reflector is formed on a multilayer of an InAlAs/InAlGaAs heterogenous thin film on the buffer layer, which has a reflective index of 1, in which a laser beam is emitted from the surface of the same.

Surface-emitting laser device

A Bragg reflector with a uniform thickness is fabricated by means of an in-situ laser reflectometer. In order to fabricate the Bragg reflector, a plurality of buffer layers are formed on a semiconductor substrate. Then, first and second epitaxial layers are alternatively grown on the buffer layers. While growing the epitaxial layers, the thickness of the first and second epitaxial layers are continuously measured by using a laser beam having the same wavelength as a reflective wavelength of the Bragg reflector. In this way, the thickness of the Bragg reflector is precisely controlled according to the measurements, so that the Bragg reflector may be fabricated uniformly with a predetermined thickness.

Method for fabricating bragg reflector using in situ laser reflectometry

A grating coupler is formed by growing an optical waveguide layer on a substrate by an epitaxial growing process such as a metalorganic chemical vapor deposition and a molecular beam deposition. The optical waveguide layer has a surface on which a cross-hatch pattern serving as the grating is continuously formed. The optical waveguide layer is formed with a material having a reflective index greater than a reflective index of the substrate or an atmosphere. Specifically, the substrate is formed with GaAs and the optical waveguide layer is formed with InGaAs. Further, the substrate is an on-substrate having an orientation coinciding with a �100! plane, so as to form the optical waveguide layer having continuous cross-hatch patterns on the surface thereof. The spacing between the cross-hatch patterns can be varied according to variation of a growth temperature of the optical waveguide layer.

Method for fabricating grating coupler

A method for sensing the completion of removal of an oxide layer from a semiconductor substrate or a super conductor by a thermal etching in real time. In the method, the time of removal of the oxide layer on the semiconductor substrate or the super conductor can ben accurately sensed. According to the method, when an oxide layer which is different from the semiconductor substrate in the refractive index is being thermally etched at a high temperature, the reflected signals of the laser beams forms a periodicity, and this periodicity is utilized so as to determine the etching rate and the time of the completion of the etching.

Method for sensing complete removal of oxide layer from substrate by

A method of sensing the concentration of a doped impurity on a semiconductor in real time and a method of sensing the change of its growth rate dependent on time among the changes of the growing conditions due to doping by using a real time analysis apparatus in growing a heterostructured semiconductor by a MOCVD method. A reflecting signal during the growth by means of a real time analysis apparatus has a periodic property, an amplitude change of a reflecting signal is dependent on an absorption coefficient when an absorption exists on an epitaxial layer, an impurity concentration can be obtained by using the relation of an absorption coefficient and an impurity concentration. In addition, if each peak is independently analyzed, the respective growth rate dependent on time are measured individually, so that the reduced growth rate dependent on time of the growth rate is sensed in a carbon doped AlAs layer.

Method of measuring doping characteristic of compound semiconductor in

A method for fabricating a defect-free compound semiconductor thin film on a dielectric thin film which oxidizes multi-semiconductor layers consisting of a hetero compound semiconductor thin film made of one of GaAs, InGaAs or InAs over a thin film containing a carbon impurity of a high concentration and made of AlGaAs series by an annealing at a vapor ambient, thereby rapidly growing a hetero-semiconductor thin film over a dielectric thin film made of Al.sub.2 O.sub.3 with no defect.

Method for fabricating defect-free compound semiconductor thin film on

An apparatus for monitoring a film growth is disclosed, in which, when a crystalline thin film is grown by applying an MOCVD (metalorganic chemical vapor deposition method), the variation of the thickness and composition due to certain factors can be detected with real time during the film growing process, and an in-situ adjustment is possible. As the optical detector for detecting two sets of reflected beams which are reflected from the film, a silicon detector and a germanium detector are used, the former being suitable for detecting short wavelength laser beams, and the latter being suitable for detecting long wavelength laser beams. Thus two different wavelengths are detected with real time, thereby measuring the thickness and composition of the film.

Apparatus for monitoring films during MOCVD

A method for growing a thin InGaAs or InAlAs layer with heavy lattice mismatching on a GaAs substrate by a MOCVD process is described. A first material gas is injected by a MOCVD process to grow a buffer layer on a GaAs substrate to a prescribed thickness. After stopping the injection of the first material gas for a few seconds, a second material gas containing a column III element is injected at a prescribed temperature. A third material gas containing a column V element is injected to grow, on the buffer layer, a thin metallic layer of a binary compound containing the column III element of a high concentration to a thickness of 2 nm or less. After a prescribed time from the injection of the third material gas, In and Ga gases or In and Al gases, mixed in the prescribed proportion are injected in an atmosphere of said third material gas to grow a thin InGaAs or InAlAs layer on the thin metallic layer.

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Daejeon, South Korea

Bun Lee