Abstract: Provided is a germanium photodetector having a germanium epitaxial layer formed without using a buffer layer and a method of fabricating the same. In the method, an amorphous germanium layer is formed on a substrate. The amorphous germanium layer is heated up to a high temperature to form a crystallized germanium layer. A germanium epitaxial layer is formed on the crystallized germanium layer.

Abstract: Provided is a mask pattern for selective area growth of a semiconductor layer and a selective area growth method for a semiconductor layer for independently controlling a growth rate and a strain of the semiconductor layer. The selective area growth method includes: forming a plurality of pairs of first mask patterns, the first mask patterns in each pair including a first open area therebetween, the first open area having a width that is wider than a distance causing overgrowth of the semiconductor layer, the pairs of the first mask patterns repeatedly arranged with a period P therebetween; wherein controlling a growth rate and a strain of the semiconductor layer formed on the first open area by adjusting the period P.

Abstract: Provided are an oscillatory circuit based on a metal-insulator transition (MIT) device that can generate a simple and very high oscillating frequency using the MIT device, and a method of driving the oscillatory circuit. The oscillatory circuit includes the MIT device that comprises an MIT thin film and an electrode thin film connected to the MIT thin film and in which an abrupt MIT is generated due to an MIT generating voltage, a resistor that is serially connected to the MIT device, an electric al power source limiting the maximum amount of an applied current and applying a direct current constant voltage to the MIT device, and a light source irradiating electromagnetic waves on the MIT device, wherein the oscillating properties are generated by irradiating the electromagnetic waves using the light source.

Abstract: Provided is a monolithic integrated composite device including: a silicon substrate which is partitioned into a silicon integrated circuit forming region and a silicon optical device forming region; a buried oxide layer which is formed locally in the silicon substrate of the silicon optical device forming region and isolates unit devices of the silicon optical device forming region; an overlay layer formed locally on the buried oxide layer; a silicon optical device formed in the silicon optical device forming region using the silicon overlay layer; a silicon integrated circuit formed in the silicon integrated circuit forming region of the silicon substrate; and wiring connecting the silicon integrated circuit and the silicon optical device or connecting the silicon optical devices or connecting the silicon integrated circuits.

Abstract: Provided is a high-speed ring optical modulator based on a silicon semiconductor, having increased optical modulation speed. The high-speed ring optical modulator includes a ring optical waveguide including a portion in which the refractive index varies, that is, a refractive index variation portion, and an optical waveguide having a constant refractive index. The refractive index variation portion comprises a bipolar transistor. Thus carriers can be supplied to and discharged from the refractive index variation portion, through which light is transmitted, at high speed, and thus the optical modulation speed can be increased.

Abstract: Provided are a photoelectric device using a PN diode and a silicon integrated circuit (IC) including the photoelectric device. The photoelectric device includes: a substrate; and an optical waveguide formed as a PN diode on the substrate, wherein a junction interface of the PN diode is formed in a direction in which light advances; and an electrode applying a reverse voltage to the PN diode, wherein N-type and P-type semiconductors of the PN diode are doped at high concentrations and the doping concentration of the N-type semiconductor is higher than or equal to that of the P-type semiconductor.

Abstract: An optical filter module for wavelength multiplexing and demultiplexing and a method of manufacturing the same are provided. The optical filter module for wavelength multiplexing and demultiplexing includes: at least one or more input waveguides; an input-stage star coupler in the form of a slab waveguide connected to the input waveguides; array waveguide which is connected to the input-stage star coupler and in which a plurality of individual waveguides, each of which has an optical path having a predetermined length different to those of the other waveguides and has a heterogeneous waveguide interval formed of a material having a different refraction index from that of a core of the waveguides, are sequentially arranged; an output-stage star coupler in the form of a slab waveguide connected to the array waveguides; and at least one or more output waveguides connected to the output-stage star coupler.

Abstract: Provided is an optical device having a strained buried channel area. The optical device includes: a semiconductor substrate of a first conductive type; a gate insulating layer formed on the semiconductor substrate; a gate of a second conductive type opposite to the first conductive type, formed on the gate insulating layer; a high density dopant diffusion area formed in the semiconductor substrate under the gate and doped with a first conductive type dopant having a higher density than the semiconductor substrate; a strained buried channel area formed of a semiconductor material having a different lattice parameter from a material of which the semiconductor substrate is formed and extending between the gate insulating layer and the semiconductor substrate to contact the high density dopant diffusion area; and a semiconductor cap layer formed between the gate insulating layer and the strained buried channel area.

Abstract: Provided is an optical device with improved phase shift and propagation loss of light without decreasing the dynamic characteristics of the optical device. The optical device includes a first semiconductor layer which is doped with a first type of conductive impurities and has a uniform thickness; a gate insulating layer which has a ? shape and is formed on a portion of the first semiconductor layer and has a thin center portion; and a second semiconductor layer which covers an upper surface of the gate insulating layer and is doped with a second type of conductive impurities opposite to the first type of conductive type impurities.

Abstract: Provided is an optical device having an edge effect with improved phase shift and propagation loss of light without decreasing the dynamic characteristics of the optical device. The optical device includes a first semiconductor layer which is doped with a first type of conductive impurities, and has a recessed groove in an upper portion thereof; a gate insulating layer covering the groove and a portion of the first semiconductor layer; and a second semiconductor layer which covers an upper surface of the gate insulating layer and is doped with a second type of conductive impurities opposite to the first type of conductive impurities.

Abstract: Provided are semiconductor integrated circuits including a grating coupler for optical communication and methods of forming the same. The semiconductor integrated circuit includes: a cladding layer disposed on a semiconductor substrate; a grating coupler including an optical waveguide on the cladding layer and a grating on the optical waveguide; and at least one reflector formed in the cladding layer below the grating.

Abstract: An interband resonant tunneling intersubband transition laser is disclosed, and includes a semiconductor substrate, and a first cladding layer, an active region structure layer and a second cladding layer formed on the semiconductor substrate. The active region structure layer includes quantum well layers and quantum barrier layers that are alternately stacked and have a broken energy bandgap. Thus, the interband resonant tunneling intersubband transition laser operates in a cascade mode in which an intersubband radiative transition and interband tunneling of carriers consecutively and repetitively occur in the active region structure layer, and thus can achieve a high output from a simple, compact structure.

Abstract: An optical filter module for wavelength multiplexing and demultiplexing and a method of manufacturing the same are provided. The optical filter module for wavelength multiplexing and demultiplexing includes: at least one or more input waveguides; an input-stage star coupler in the form of a slab waveguide connected to the input waveguides; array waveguide which is connected to the input-stage star coupler and in which a plurality of individual waveguides, each of which has an optical path having a predetermined length different to those of the other waveguides and has a heterogeneous waveguide interval formed of a material having a different refraction index from that of a core of the waveguides, are sequentially arranged; an output-stage star coupler in the form of a slab waveguide connected to the array waveguides; and at least one or more output waveguides connected to the output-stage star coupler.

Abstract: Provided is a high-speed ring optical modulator based on a silicon semiconductor, having increased optical modulation speed. The high-speed ring optical modulator includes a ring optical waveguide including a portion in which the refractive index varies, that is, a refractive index variation portion, and an optical waveguide having a constant refractive index. The refractive index variation portion comprises a bipolar transistor. Thus carriers can be supplied to and discharged from the refractive index variation portion, through which light is transmitted, at high speed, and thus the optical modulation speed can be increased.

Abstract: Provided is a silicon array waveguide grating (AWG) device comprising a silicon array waveguide in which a plurality of optical waveguides formed of a lower cladding layer, a silicon core, and an upper cladding layer are arranged, wherein the variation of the refractive index of the silicon core is positive, and the upper cladding layer is formed of polymer, the variation of refractive index of which according to temperature is negative, which is opposite to the silicon core, and the cross-section of the silicon core varies between different areas to adjust the variation of the effective refractive index of the optical waveguide according to temperature.

Abstract: Provided is a 2-terminal semiconductor device that uses an abrupt MIT semiconductor material layer. The 2-terminal semiconductor device includes a first electrode layer, an abrupt MIT semiconductor organic or inorganic material layer having an energy gap less than 2eV and holes in a hole level disposed on the first electrode layer, and a second electrode layer disposed on the abrupt MIT semiconductor organic or inorganic material layer. An abrupt MIT is generated in the abrupt MIT semiconductor material layer by a field applied between the first electrode layer and the second electrode layer.

Abstract: A current-jump-control circuit including an abrupt metal-insulator phase transition device is proposed, and includes a source, the abrupt metal-insulator phase transition device and a resistive element. The abrupt metal-insulator phase transition device includes first and second electrodes connected to the source, and shows an abrupt metal-insulator phase transition characteristic of a current jump when an electric field is applied between the first electrode and the second electrode. The resistive element is connected between the source and the abrupt metal-insulator phase transition device to control a jump current flowing through the abrupt metal-insulator phase transition device. According to the above current control circuit, the abrupt metal-insulator phase transition device can be prevented from being failed due to a large amount of current and thus the current-jump-control circuit can be applied in various application fields.

Abstract: A current-jump-control circuit including an abrupt metal-insulator phase transition device is proposed, and includes a source, the abrupt metal-insulator phase transition device and a resistive element. The abrupt metal-insulator phase transition device includes first and second electrodes connected to the source, and shows an abrupt metal-insulator phase transition characteristic of a current jump when an electric field is applied between the first electrode and the second electrode. The resistive element is connected between the source and the abrupt metal-insulator phase transition device to control a jump current flowing through the abrupt metal-insulator phase transition device. According to the above current control circuit, the abrupt metal-insulator phase transition device can be prevented from being failed due to a large amount of current and thus the current-jump-control circuit can be applied in various application fields.