EP-4737991-A1 - OPTICAL MODULATORS, METHODS OF MANUFACTURING THE SAME AND APPARATUS INCLUDING OPTICAL MODULATOR

EP4737991A1EP 4737991 A1EP4737991 A1EP 4737991A1EP-4737991-A1

Abstract

An optical modulator may include: a first semiconductor layer; a second semiconductor layer configured as a micro-disk, the second semiconductor layer being on the first semiconductor layer, and the second semiconductor layer including a first doping region and a second doping region, wherein a doping concentration of the first doping region is higher than a doping concentration of the second doping region; a first optical waveguide adjacent to the second semiconductor layer; a first electrode layer on the first doping region; and a second electrode layer on the first doping region and spaced apart from the first electrode layer, wherein the second semiconductor layer includes at least one recess, the second semiconductor layer has at least one step difference due to the at least one recess, and the first doping region, the second doping region, and the at least one recess comprise respective circular shapes, wherein all of the respective circular shapes are concentric with respect to one another.

Inventors

LEE, DUHYUN
NAMKOONG, KAK
Park, Jaechul

Assignees

Samsung Electronics Co., Ltd

Dates

Publication Date: 20260506
Application Date: 20251105

Claims (15)

An optical modulator comprising: a first semiconductor layer; a second semiconductor layer configured as a micro-disk, the second semiconductor layer being on the first semiconductor layer, and the second semiconductor layer comprising a first doping region and a second doping region, wherein a doping concentration of the first doping region is higher than a doping concentration of the second doping region; a first optical waveguide adjacent to the second semiconductor layer; a first electrode layer on the first doping region; and a second electrode layer on the first doping region and spaced apart from the first electrode layer, wherein the second semiconductor layer comprises at least one recess, wherein the second semiconductor layer has at least one step difference due to the at least one recess, wherein each of the first doping region, the second doping region, and the at least one recess comprises a circular shape, wherein the circular shapes of the first doping region, the second doping region, and the at least one recess are concentric with respect to one another, wherein the second doping region is on the outside of the first doping region and surrounds the first doping region in the horizontal plane, and wherein the first electrode layer and the second electrode layer are on different doping regions from each other of the first doping region.
The optical modulator of claim 1, wherein the at least one recess of the second semiconductor layer comprises a first recess, a lower surface of the first recess comprises an upper surface of the first doping region and an upper surface of the second doping region, a side surface of the first recess comprises an inner side surface of the second doping region, and a first step difference, of the at least one step difference, is in the second doping region due to the first recess.
The optical modulator of claim 2, wherein the first doping region comprises an N-doped region doped with an N-type dopant and a P-doped region doped with a P-type dopant, the second doping region comprises an N-doped region doped with an N-type dopant and a P-doped region doped with a P-type dopant,the lower surface of the first recess comprises an upper surface of the N-doped region of the first doping region, an upper surface of the P-doped region of the first doping region, and a first upper surface of the P-doped region of the second doping region, the side surface of the first recess comprises an inner side surface of the P-doped region of the second doping region, and the first step difference corresponds to a height difference between the first upper surface of the P-doped region of the second doping region and a second upper surface of the second semiconductor layer located higher than the first upper surface.
The optical modulator of claim 2, wherein the first doping region comprises an N-doped region doped with an N-type dopant and a P-doped region doped with a P-type dopant, the second doping region comprises an N-doped region doped with an N-type dopant and a P-doped region doped with a P-type dopant, the lower surface of the first recess comprises an upper surface of the N-doped region of the first doping region, an upper surface of the P-doped region of the first doping region, and a first upper surface of the P-doped region of the second doping region, the side surface of the first recess comprises the inner side surface of the P-doped region of the second doping region and an inner side surface of the N-doped region of the second doping region, the first step difference corresponds to a height difference between the first upper surface of the P-doped region of the second doping region and the upper surface of the N-doped region of the second doping region, the N-doped region of the second doping region is between the P-doped region and the first semiconductor layer, and surrounds the P-doped region of the second doping region outside the first recess in a horizontal direction, and an outer side surface of the N-doped region of the second doping region is a side surface of the second semiconductor layer.
The optical modulator of claim 3 or 4, wherein the P-doped region of the first doping region and the N-doped region of the first doping region are concentric, an internal step difference, of the at least one step difference, exists between a center of the N-doped region of the first doping region, in a horizontal direction, and an edge of the N-doped region of the first doping region, in the horizontal direction, a thickness of the edge of the N-doped region of the first doping region is less than a thickness of the center of the N-doped region of the first doping region, and the P-doped region of the first doping region overlaps with the edge of the N-doped region of the first doping region in a vertical direction, and an upper surface of the P-doped region of the first doping region is coplanar with respect to the upper surface of the N-doped region of the first doping region.
The optical modulator of claim 2, wherein the at least one recess of the second semiconductor layer is a plurality of recesses comprising the first recess and a second recess inside the first recess, and the second recess is concentric with respect to the first recess, the at least one step difference comprises a plurality of step differences comprising the first step difference and a second step difference, a side surface of the second recess and a lower surface of the second recess comprise surfaces of the first doping region, respectively, the second step difference is inside the first recess due to the second recess, and the first step difference and the second step difference are spaced apart from each other in a horizontal direction parallel to the upper surface of the first semiconductor layer, and a height of the first step difference from the upper surface of the first semiconductor layer is different from a height of the second step difference from the upper surface of the first semiconductor layer.
The optical modulator of claim 6, wherein the first doping region comprises an N-doped region doped with an N-type dopant and a P-doped region doped with a P-type dopant, each of the N-doped region and the P-doped region comprises a circular shape that is concentric with respect to one another, the lower surface of the second recess comprises an upper surface of the N-doped region, the side surface of the second recess comprises an inner side surface of the P-doped region, and the second step difference corresponds to a height difference between the upper surface of the N-doped region of the first doping region and the upper surface of the P-doped region of the first doping region, and wherein preferably: the N-doped region and the P-doped region are spaced apart from each other in a vertical direction crossing the upper surface of the first semiconductor layer, a part of the second doping region is between the N-doped region and the P-doped region, the side surface of the second recess comprises an inner side surface of the part of the second doping region and an inner side surface of the P-doped region of the first doping region, the second doping region comprises an N-doped region doped with an N-dopant and a P-doped region doped with a P-dopant, the N-doped region of the second doping region and the P-doped region of the second doping region are concentric, the lower surface of the first recess comprises the upper surface of the P-doped region of the second doping region, and the side surface of the first recess comprises the inner side surface of the P-doped region of the second doping region.
The optical modulator of any of the preceding claims, wherein the at least one recess of the second semiconductor layer comprises a first recess, a lower surface of the first recess comprises an upper surface of the second doping region, a side surface of the first recess comprises a first inner side surface of the second doping region, and a first step difference, of the at least one step difference, is in the second doping region due to the first recess.
The optical modulator of claim 8, wherein the at least one recess of the second semiconductor layer is a plurality of recesses comprising the first recess and a second recess inside the first recess, and the second recess is concentric with respect to the first recess, the at least one step difference comprises a plurality of step differences comprising the first step difference and a second step difference, a lower surface of the second recess comprises a surface of the first doping region, a side surface of the second recess comprises a second inner side surface of the second doping region, the second step difference is inside the first recess due to the second recess, and the first step difference and the second step difference are spaced apart from each other in a horizontal direction parallel to an upper surface of the first semiconductor layer, and a height of the first step difference from the upper surface of the first semiconductor layer is different from a height of the second step difference from the upper surface of the first semiconductor layer.
The optical modulator of any of the preceding claims, wherein the at least one recess of the second semiconductor layer comprises a first recess, a side surface of the first recess and a lower surface of the first recess comprise surfaces of the first doping region, respectively, and a first step difference, of the at least one step difference, is in the first doping region due to the first recess.
The optical modulator of claim 1, further comprising: a second optical waveguide spaced apart from the second semiconductor layer, wherein the second semiconductor layer is between the first optical waveguide and the second optical waveguide.
A method of manufacturing an optical modulator, the method comprising: forming, on a first semiconductor layer, a second semiconductor layer in a shape of a micro-disk; forming a first doping region in the second semiconductor layer, the first doping region including a circular shape; forming a second doping region in the second semiconductor layer around the first doping region, wherein the second doping region is concentric with the first doping region and surrounds the first doping region in horizontal directions; forming a first step difference in one from among the first doping region and the second doping region; and forming an electrode layer on the first doping region, wherein a doping concentration of the first doping region is higher than a doping concentration of the second doping region.
The method of claim 12, wherein the first step difference is formed at least in the first doping region.
The method of claim 13, further comprising forming a second step difference in the second doping region.
The method of claim 14, wherein the forming the second doping region comprises: forming a first doping layer; forming a second doping layer on the first doping layer, the second doping layer including the second step difference; and forming a third doping layer on an outer portion of the second step difference of the second doping layer, the third doping layer contacting the first doping layer, wherein a dopant type of the first doping layer is the same as a dopant type of the third doping layer.

Description

FIELD OF THE INVENTION The present disclosure relates to an optical device, and more specifically, to an optical modulator of a photonic integrated circuit (PIC), a method of manufacturing the same, and an apparatus including the optical modulator. BACKGROUND OF THE INVENTION In a silicon (Si)-based PIC, a Mach-Zehnder interferometer (MZI) and a micro-ring modulator (MRM) may be used as an optical modulator. For wideband information transmission, technology for increasing the modulation speed of optical modulators, and for parallel processing of signals, wavelength division multiplexing (WDM) technology, in which multiple wavelength signals are simultaneously transmitted through a single waveguide, may be applied. Because an MRM modulates only light with wavelengths that match the resonant wavelength of the micro-ring, it is possible to construct a WDM optical circuit relatively simply, and because high-speed modulation is possible, the MRM may be used. In order to expand the WDM bandwidth, the diameter of the micro-ring may be gradually reduced, but in this process, the curvature of the micro-ring increases, which may result in optical loss. Accordingly, a method of configuring a resonator in the form of a micro-disk as an alternative to a micro-ring has been introduced, but this method may include an element that affects the optical modulation speed. SUMMARY OF THE INVENTION One or more embodiments of the disclosure provide an optical modulator capable of increasing the optical modulation speed. One or more embodiments of the disclosure provide an optical modulator capable of mode filtering. One or more embodiments of the disclosure provide a method of manufacturing the optical modulator. One or more embodiments of the disclosure provide an apparatus including the optical modulator. Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the example embodiments of the disclosure. According to some example embodiments, an optical modulator may include a first semiconductor layer; a second semiconductor layer configured as a micro-disk, the second semiconductor layer being on the first semiconductor layer, and the second semiconductor layer including a first doping region and a second doping region, wherein a doping concentration of the first doping region is higher than a doping concentration of the second doping region; a first optical waveguide adjacent to the second semiconductor layer; a first electrode layer on the first doping region; and a second electrode layer on the first doping region and spaced apart from the first electrode layer, wherein the second semiconductor layer includes at least one recess, the second semiconductor layer has at least one step difference due to the at least one recess, and each of the first doping region, the second doping region, and the at least one recess includes a circular shape that is concentric with respect to one another. Alternatively or additionally, according to some example embodiments, a method of manufacturing an optical modulator may include forming, on a first semiconductor layer, a second semiconductor layer in a shape of a micro-disk; forming a first doping region in the second semiconductor layer, the first doping region including a circular shape; forming a second doping region in the second semiconductor layer around the first doping region, wherein the second doping region is concentric with the first doping region and surrounds the first doping region in horizontal directions; forming a first step difference in one from among the first doping region and the second doping region; and forming an electrode layer on the first doping region, wherein a doping concentration of the first doping region is higher than a doping concentration of the second doping region. Alternatively or additionally, according to some example embodiments, an electronic apparatus may include a light source; an optical waveguide that is configured to transmit light emitted from the light source; a semiconductor layer adjacent to the optical waveguide, the semiconductor layer configured as a micro-disk; and an amplifier configured to amplify the light transmitted by the optical waveguide, wherein the semiconductor layer includes a first doping region and a second doping region, wherein the first doping region and the second doping region are at a center of the semiconductor layer in a horizontal direction, wherein the semiconductor layer includes at least one additional doping region that is outside of the first doping region and the second doping region in the horizontal direction, wherein a dopant type of the first doping region is opposite from a dopant type of the second doping region, wherein a doping concentration of the first doping region and a doping concentration of the second doping region is greater than a doping concentration of the at least one additional d