KR20180028327A - Electro-absorption modulator, and optical communication system - Google Patents

Abstract

An embodiment of the present invention relates to an electric field absorption modulator and an optical communication system capable of improving light loss. The modulator comprises: a first conductive semiconductor layer; an active layer on the first conductive semiconductor layer; a second conductive semiconductor layer on the active layer; a first electrode disposed on the first conductive semiconductor layer and including a first contact portion connected with the first conductive semiconductor layer; and a second electrode disposed on the second conductive semiconductor layer and spaced apart from the first electrode. The second contact portion is disposed on the active layer and is in contact with the second conductive semiconductor layer. The area of the second contact portion can be less than or equal to 30% of the area of the active layer.

Description

TECHNICAL FIELD [0001] The present invention relates to an electro-absorption modulator and an optical communication system,

Embodiments relate to an electro-absorption modulator and an optical communication system including the same.

Semiconductor devices including compounds such as GaN and AlGaN have many merits such as wide and easy bandgap energy, and can be used variously as light emitting devices, light receiving devices, and various diodes.

Particularly, a light emitting device such as a light emitting diode or a laser diode using a semiconductor material of Group 3-5 or 2-6 group semiconductors can be applied to various devices such as a red, Blue, and ultraviolet rays. By using fluorescent materials or combining colors, it is possible to realize a white light beam with high efficiency. Also, compared to conventional light sources such as fluorescent lamps and incandescent lamps, low power consumption, , Safety, and environmental friendliness.

In addition, when a light-receiving element such as a photodetector or a solar cell is manufactured using a semiconductor material of Group 3-5 or Group 2-6 compound semiconductor, development of a device material absorbs light of various wavelength regions to generate a photocurrent , It is possible to use light in various wavelength ranges from the gamma ray to the radio wave region. It also has advantages of fast response speed, safety, environmental friendliness and easy control of device materials, so it can be easily used for power control or microwave circuit or communication module.

Accordingly, the semiconductor device can be replaced with a transmission module of an optical communication means, a light emitting diode backlight replacing a cold cathode fluorescent lamp (CCFL) constituting a backlight of an LCD (Liquid Crystal Display) display device, White light emitting diodes (LEDs), automotive headlights, traffic lights, and gas and fire sensors. In addition, semiconductor devices can be applied to high frequency application circuits, other power control devices, and communication modules.

A semiconductor device using optical communication means is typically an electric field absorption modulator (EAM) using a short wavelength of a laser diode. However, it is difficult to fabricate the laser diode, and it is difficult to align the EAM and the laser diode by a narrow beam.

One of the problems of the embodiment is to provide an electric field absorption modulator having an electrode structure capable of realizing a uniform electric field distribution.

It is another object of the present invention to provide an electric field absorption modulator capable of realizing a high-speed operation of 10 Gbps or more.

Further, one of the problems of the embodiment is to provide an electric field absorption modulator and an optical communication system capable of improving a modulation function by improving an absorption ratio.

Another object of the present invention is to provide an electro-absorption modulator and an optical communication system capable of improving light efficiency by arranging a reflective layer on the electric-field-absorbing structure layer to improve light loss.

It is another object of the present invention to provide an electro-absorption modulator and an optical communication system capable of improving light loss by integrating a nitride-based light emitting device and a nitride-based electric field absorption modulator with a substrate interposed therebetween.

In an embodiment, the electroabsorption modulator includes a first conductivity type semiconductor layer; An active layer on the first conductive semiconductor layer; A second conductive semiconductor layer on the active layer; A first electrode disposed on the first conductive type semiconductor layer and including a first contact portion in contact with the first conductive type semiconductor layer; And a second electrode disposed on the second conductive type semiconductor layer and spaced apart from the first electrode, wherein the second electrode is disposed on the active layer, and the second electrode is disposed on the active layer, And the area of the second contact portion may be 30% or less of the area of the active layer.

Further, the electro-absorption modulator of the embodiment includes a light-emitting portion of a nitride-based semiconductor, a light-modulating portion of a nitride-based semiconductor, and a substrate, wherein a light-modulated portion of the nitride-based semiconductor is grown on one surface of the substrate, Emitting portion of the semiconductor can be grown and integrated in the vertical direction.

Embodiments may include an electrode structure symmetrical to each other to realize a uniform electric field distribution, thereby improving the reliability of light modulation.

In addition, the embodiment can realize a high-speed operation of 10 Gbps or higher at a short distance within 100 m by using a nitride-based semiconductor which is inexpensive in manufacturing method and manufacturing cost.

In addition, the embodiment can improve the modulation function by improving the absorptivity of the electro-absorption modulator by the structure of the contact portion disposed on the active layer.

1 is a plan view showing an electric field absorption modulator according to a first embodiment.
Fig. 2 is a cross-sectional view showing the field-effect absorption modulator of the first embodiment in which AA of Fig. 1 is cut.
3 is a cross-sectional view showing an electric field absorption modulator of the first embodiment in which BB of FIG. 1 is cut.
4 is a cross-sectional view showing an electro-absorption modulator of the second embodiment in which AA of FIG. 1 is cut.
5 is a cross-sectional view showing an electro-absorption modulator of the second embodiment in which BB in Fig. 1 is cut.
6 is a plan view showing an electro-absorption modulator according to the third embodiment.
FIG. 7 is a cross-sectional view showing an electric field absorption modulator in which CC in FIG. 6 is cut.
8 is a plan view showing an electric field absorption modulator according to the fourth embodiment.
9 is a cross-sectional view showing the electro-absorption modulator in which DD in FIG. 8 is cut.
10 is a plan view showing an electro-absorption modulator according to a fifth embodiment.
11 is a cross-sectional view showing an electric field absorption modulator in which EE of FIG. 10 is cut.
12 is a cross-sectional view showing an electro-absorption modulator according to a sixth embodiment.
13 is a cross-sectional view showing an electro-absorption modulator according to a seventh embodiment.
14 is a diagram showing a configuration of an optical communication system according to an embodiment.

The embodiments may be modified in other forms or various embodiments may be combined with each other, and the scope of the present invention is not limited to each embodiment described below.

Although not described in the context of another embodiment, unless otherwise described or contradicted by the description in another embodiment, the description in relation to another embodiment may be understood.

For example, if the features of configuration A are described in a particular embodiment, and the features of configuration B are described in another embodiment, even if the embodiment in which configuration A and configuration B are combined is not explicitly described, It is to be understood that they fall within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

In the description of the embodiment according to the present invention, in the case of being described as being formed "on or under" of each element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed between the two elements. Also, when expressed as "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

The semiconductor device may include various electronic devices such as a light emitting device, a light receiving device, and an optical modulator. The light emitting device, the light receiving device, and the optical modulator may include the first conductivity type semiconductor layer, the active layer, and the second conductivity type semiconductor layer .

The semiconductor device according to the present embodiment may be an optical modulator. For example, the optical modulator may be an electro-absorption modulator (EAM).

The electroabsorption modulator (EAM) can modulate the optical signal emitted from the output end by absorption difference or absorption and transmission according to the electric field of the semiconductor structure.

FIG. 1 is a plan view showing a semiconductor device according to a first embodiment, FIG. 2 is a sectional view showing a semiconductor device of the first embodiment in which AA in FIG. 1 is cut, and FIG. 3 is a cross- 1 is a cross-sectional view showing a semiconductor device of one embodiment.

The electric field absorbing modulator (EAM, 100A) according to the first embodiment shown in FIGS. 1 to 3 can modulate light incident from the outside using an absorption difference according to an electric field. One of the problems of the embodiment is to realize a uniform electric field distribution and to improve the reliability of optical modulation. In addition, one of the problems of the embodiment can realize a high-speed operation of 10 Gbps or more. In addition, one of the problems of the embodiment is to improve the modulation function by improving the absorptivity of the electrode at the time of transmission of light.

For this, an embodiment includes an optical modulation structure layer 120 on a substrate 110, first to fourth electrodes 130a, 140a, 130b, and 140b disposed on the optical modulation structure layer 120, And a reflective layer 160 disposed between the optical modulation structure layer 120 and the first to fourth electrodes 130a, 140a, 130b, and 140b.

≪ Optical Modulation Structure Layer >

The optical modulation structure layer includes a first conductivity type semiconductor layer 121 on the substrate 110, an active layer 123 on the first conductivity type semiconductor layer 121, a second conductivity type semiconductor layer on the active layer 123, Layer 125 and a conductive layer 127 on the second conductive type semiconductor layer 125. [

One of the problems of the embodiment is to realize a high-speed operation of 10 Gbps or more. For this, the active layer 123 may include an area of 30% or less of the upper surface area of the optical modulation structure layer 120. Specifically, the active layer 123 may include an area of 0.5% to 5% of the upper surface area of the optical modulation structure layer 120, and the smaller the area of the active layer 123, the smaller the capacitance value. Can be implemented. If the area of the active layer 123 is less than 0.5% of the upper surface area of the optical modulation structure layer 120, it may be difficult to secure a process margin for the placement of other components. When the upper surface area of the active layer 123 exceeds 30% of the upper surface area of the optical modulation structure layer 120, the capacitance value becomes too large and high-speed operation may be difficult. The area of the active layer 123 can be controlled according to the application field of the product and it is advantageous to realize high-speed operation when the area is 5% or less of the area of the upper surface of the optical modulation structure layer 120.

The active layer 123 may be disposed at the center of the first conductive semiconductor layer 121, but is not limited thereto. For example, the active layer 123 may be disposed adjacent to one side of the first conductive semiconductor layer 121. The top view of the active layer 123 may have a circular structure, but the present invention is not limited thereto. For example, the top view of the active layer 123 may be an elliptical or polygonal structure.

The active layer 123 is formed so that electrons (or holes) injected through the first conductivity type semiconductor layer 121 and holes (or electrons) injected through the second conductivity type semiconductor layer 125 meet with each other, The light can be absorbed or transmitted by a band gap difference of an energy band according to a material of the light emitting layer 123. In the case of absorbing light, the intensity of light output from the output end may be weak to be detected at the detection end, and the intensity of light output at the output end when the light is transmitted may be sufficient to be detected at the detection end. Therefore, the active layer 123 may serve to absorb or transmit light so that the optical signal input to the active layer 123 can be modulated at the output terminal.

The active layer 123 may be formed of a compound semiconductor. The active layer 123 may be formed of at least one of Group 3-Group-5 or Group-6-Group compound semiconductors. When the active layer 123 is implemented as a multi-well structure, the active layer 123 may include a plurality of alternately arranged well layers and a plurality of barrier layers, but the present invention is not limited thereto. The active layer 123 may be disposed of a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + y? InGaN / AlGaN, InGaN / InGaN, InGaN / InGaN, AlGaAs / GaAs, InGaAs / GaAs, InGaP / GaP, AlInGaP / InGaP, InGaN / AlGaN, AlGaN / AlGaN, Pair < / RTI >

The substrate 110 may be a translucent, conductive substrate, or an insulating substrate. For example, the substrate 110 may include at least one of sapphire (Al ₂ O ₃ ), SiC, Si, GaAs, GaN, ZnO, GaP, InP, Ge and Ga ₂ O ₃ . A plurality of protrusions (not shown) may be formed on the lower surface of the substrate 110. Each of the plurality of protrusions may include at least one of a hemispherical shape, a polygonal shape, and an ellipse shape, Lt; / RTI > The plurality of protrusions may refract light incident from the lower surface of the substrate 110 to improve light efficiency incident on the active layer 123.

The electroabsorption modulator 100A according to the first embodiment may include a first conductivity type semiconductor layer 121, an active layer 123 and a second conductivity type semiconductor layer 125 disposed on a substrate 110 . A conductive layer 127 may be disposed on the second conductive semiconductor layer 125. The conductive layer 127 may be electrically connected to the second conductive type semiconductor layer 125 and may be formed of a material having high light transmittance. In the case of a material having high light transmittance,

The conductive layer 127 may be a single layer or a multi-layered material having excellent electrical contact with the second conductive type semiconductor layer 125. For example, the conductive layer 127 may be formed of Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf, Be, Ge, indium tin oxide (ITO) zinc oxide (IZTO), indium zinc oxide (IZTO), indium zinc oxide (IZO), indium gallium zinc oxide (IGTO), aluminum zinc oxide (AZO), antimony tin oxide ZnO, IrOx, RuOx, NiO, RuOx / ITO, Ni / IrOx / Au, and Ni / IrOx / Au. IrOx / Au / ITO, and the present invention is not limited to these materials.

The first conductive semiconductor layer 121 may be disposed on one side of the substrate 110. The first conductivity type semiconductor layer 121 may be formed of at least one of Group III-V-VI or Group V-VI compound semiconductors. The first conductive semiconductor layer 121 may be a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + As shown in FIG. The first conductive semiconductor layer 121 may include at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP and AlGaInP. The first conductive semiconductor layer 121 may be an n-type semiconductor layer doped with an n-type dopant such as Si, Ge, Sn, Se, or Te.

The second conductive semiconductor layer 125 may be disposed on the active layer 123. The second conductive semiconductor layer 125 includes an area corresponding to the active layer 123, but is not limited thereto. The second conductivity type semiconductor layer 125 may be formed of at least one of Group III-V-VI or Group V-VI compound semiconductors. The second conductivity type semiconductor layer 125 may be a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + As shown in FIG. The second conductive semiconductor layer 125 may include at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP and AlGaInP. The first conductive semiconductor layer 125 may be a p-type semiconductor layer doped with a p-type dopant such as Mg, Zn, Ca, Sr, or Ba.

≪ First to fourth electrodes >

One of the problems of the embodiment is to realize a uniform electric field distribution and to improve the reliability of optical modulation. To this end, the electroabsorption modulator 100A according to the first embodiment may include first to fourth electrodes 130a, 150a, 130b and 150b symmetrical to each other. The first to fourth electrodes 130a, 150a, 130b and 150b of the first embodiment are symmetrical with respect to each other with the active layer 123 interposed therebetween, so that a uniform electric field distribution of the active layer 123 can be realized. In addition, one of the problems of the embodiment is to improve the absorption function by the electrode disposed on the active layer 123 at the time of transmission of light, thereby improving the modulation function. The electroabsorption modulator 100A according to the first embodiment includes a second contact portion 151a of the second electrode 150a disposed on the active layer 123 and a fourth contact portion 151b of the fourth electrode 150b. May include an area of 30% or less of the area of the upper surface of the active layer 123. The electroabsorption modulator 100A according to the first embodiment is provided with the second and fourth contact portions 151a and 151b having an area of 30% or less of the area of the upper surface of the active layer 123 to minimize the light absorbed by the electrodes The modulation function can be improved.

The first and third electrodes 130a and 130b may be electrically connected to the first conductivity type semiconductor layer 121. The second and fourth electrodes 150a and 150b may be electrically connected to the second conductive type semiconductor layer 125.

The first and third electrodes 130a and 130b are symmetrical in the first and second directions X and X 'with the active layer 123 therebetween, and the second and fourth electrodes 150a and 150b And may be symmetrical in the third and fourth directions Y and Y 'orthogonal to the first and second directions X and X' with the active layer 123 therebetween. Here, the first and second directions X and X 'may correspond to the short axis SA of the electroabsorption modulator 100A, and the third and fourth directions Y and Y' May correspond to the long axis (LA) of the main body 100A.

The first electrode 130a may include a first electrode pad 133a and a first contact 131a. The third electrode 130b may include a third electrode pad 133b and a third contact 131b.

The first and third electrode pads 133a and 133b may be symmetrical with respect to each other in the first and second directions X and X '. The first electrode pad 133a may be spaced apart from the outside of the active layer 123 in the first direction X. Referring to FIG. The second electrode pad 133b may be spaced apart from the outside of the active layer 123 in a second direction X '. The first electrode pad 133a is spaced apart from the outer sides of the second and fourth electrodes 150a and 150b in a first direction X and the third electrode pad 133b is spaced apart from the second and fourth electrodes 150a and 150b. May be spaced apart from the outside of the first electrodes 150a and 150b in the second direction X. The first contacts 131a may be disposed within the first electrode pad 133a. The third contact portion 131b may be disposed in the third electrode pad 133b. The first and third contact portions 131a and 131b may be in direct contact with the first conductive semiconductor layer 121. The first and third contact portions 131a and 131b may be in contact with the upper surface of the first conductive type semiconductor layer 121 exposed from the reflective layer 160. The first and third contact portions 131a and 131b may be disposed on the short axis SA, but the present invention is not limited thereto. The first and third contact portions 131a and 131b may be separated from the active layer 123 by a predetermined distance. The first and third contact portions 131a and 131b are spaced apart from the active layer 123 by a predetermined distance to concentrate the current concentrated at the shortest distance between the first and third contact portions 131a and 131b and the active layer 123 Can be improved.

≪ Second and fourth contacts >

One of the problems to be solved in the embodiment is to improve the absorption function by the electrode at the time of transmission of light, thereby improving the modulation function. The second electrode 150a may include a second electrode pad 153a and a second contact portion 151a and the fourth electrode 150b may include a fourth electrode pad 153b and a fourth contact portion 151b. That is, in the embodiment, the second and fourth contact portions 151a and 151b are disposed on the edge region of the active layer 123 to improve the light absorbed by the second and fourth contact portions 151a and 151b have.

The second electrode pad 153a may be spaced apart from the outside of the active layer 123 in the third direction Y. [ The fourth electrode pad 153b may be spaced apart from the outside of the active layer 123 in the fourth direction Y '. The second and fourth electrode pads 153a and 153b may include a width that increases as the distance from the active layer 123 increases. However, the present invention is not limited thereto. The second electrode 150a may include a first connection part 155a connecting the second electrode pad 153a and the second contact part 151a and the fourth electrode 150b may include a fourth connection part 155a, And a second connection portion 155b connecting the pad 153b and the fourth contact portion 151b.

The second contact portion 151a may be disposed on the active layer 123 and may overlap the edge region of the active layer 123 in the vertical direction. The second contact portion 151a may be in direct contact with the upper edge region of the conductive layer 127. The second contact portion 151a may include two ends 151e-1 symmetrical in the first and second directions X and X 'from the first connection portion 155a. The second contact portion 151a may include first and second side portions 151s-1 and 151s-2. The first side 151 s-1 may face the outside of the active layer 123. The second side 151s-2 may be disposed on the opposite side of the first side 151s-1 and may face the fourth contact 151b. The radius of curvature of the first side 151s-1 may be greater than the radius of curvature of the second side 151s-2. Here, the outer radius of curvature of the active layer 123 may be greater than the radius of curvature of the first side 151s-1. The first and second sides 151s-1 and 151s-2 may be connected to the first end 151e-1.

The second contact portion 151a overlaps a part of the emission portion EA of the active layer 123 and is disposed in the edge region of the active layer 123 to minimize the absorption of light. The first width W1 from the second side 151s-2 of the second contact portion 151a to the outside of the active layer 123 may be 20 占 퐉 or less. When the first width W1 is more than 20 mu m, the modulation reliability due to absorption difference of light may be lowered by absorbing the light concentrated at the center of the active layer 123. [

The fourth contact portion 151b includes a second end 151e-2 symmetrical to the second contact portion 151a and third and fourth sides 151s-3 and 151s-4, It is possible to adopt the technical features of the first embodiment 151a.

Here, the first and third sides 151s-1 and 151s-3 are connected to the fifth side 133s-1 of the first electrode 130a and the sixth side 133s-2 of the third electrode 130b And may face the fifth and sixth sides 133s-1 and 133s-2. The fifth and sixth sides 133s-1 and 133s-2 may be spaced apart from the outside of the active layer 123 and may include a radius of curvature larger than that of the active layer 123.

The second and fourth contact portions 151a and 151b of the electroabsorption modulator 100A of the first embodiment include an area of 30% or less of the area of the upper surface of the active layer 123, thereby realizing an overall uniform electric field. The electroabsorption modulator 100A of the first embodiment includes a first width W1 of 20 mu m or less from the outside of the active layer 123 to the second and fourth contact portions 151a and 151b, It is possible to reduce the absorption rate by the second and fourth contact portions 151a and 151b, thereby improving the reliability of the optical modulation.

<Reflective Layer>

One of the problems of the embodiment is to improve the optical efficiency by improving the optical loss. To this end, the electroabsorption modulator 100A according to the first embodiment may include a reflection layer 160 for reflecting light to the active layer 123. [

The reflective layer 160 may be disposed on the optical modulation structure layer 120. The reflective layer 160 may extend to the upper edge region of the second conductivity type semiconductor layer 125 while exposing the emission portion EA of the optical modulation structure layer 120. The reflective layer 160 may be in direct contact with the upper edge region of the conductive layer 127.

The reflective layer 160 may be vertically overlapped with the upper edge region of the active layer 123. The width of the reflective layer 160 vertically overlapped with the active layer 123 may be 5 탆 to 6 탆. When the width of the reflective layer 160 vertically overlapped with the active layer 123 is less than 5 탆, peeling may occur at the end of the reflective layer 160 on the active layer 123. When the width of the reflective layer 160 vertically overlapped with the active layer 123 is more than 6 mu m, the area of the exit portion EA of the active layer 123 is reduced and a part of the transmitted light can be reflected, It is possible to improve the reliability of the optical modulation due to the difference between the absorption and transmission of light.

The reflective layer 160 of the first embodiment extends to the edge region of the active layer 123 to improve the filling of the reflective layer 160 and to direct the light traveling in the outer and lower directions of the active layer 123 toward the active layer 123 So that the light loss can be improved.

The reflective layer 160 may include a metal layer 165, a first insulating layer 161, and a second insulating layer 163. The metal layer 165 may reflect light incident from the substrate 110 to the active layer 123. The metal layer 165 may be disposed between the first and second insulating layers 161 and 163. The metal layer 165 may extend to an edge region of the active layer 123. The metal layer 165 may be closed from the outside by the first and second insulating layers 161 and 163. The metal layer 165 may include at least one layer of a material selected from the group consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf and combinations thereof.

The first insulating layer 161 may be in direct contact with the optical modulation structure layer 120. The upper surface of the first insulating layer 161 may be wider than the upper surface of the metal layer 165. The second insulating layer 163 may be disposed on the metal layer 165 and extend to an edge region of the first insulating layer 161. The first insulating layer 161 may include a third end 161e and the second insulating layer 163 may include a fourth end 163e. The third and fourth ends 161e and 163e may contact a part of the second and fourth contact portions 151a and 151b. The first and second insulating layers 161 and 163 may include an insulating material selected from SiO ₂ , SiO _x , SiO _x N _y , Si ₃ N ₄ , Al ₂ O ₃ , and TiO ₂ .

The reflection layer 165 of the first embodiment is not limited to the first embodiment and can be applied to the electro-absorption modulators of other embodiments of Figs.

FIG. 4 is a cross-sectional view showing the electro-absorption modulator of the second embodiment cut along line A-A of FIG. 1, and FIG. 5 is a cross-sectional view of the electro-absorption modulator of the second embodiment taken along line B-B of FIG.

The electroabsorption modulator 100B of the second embodiment shown in Figs. 4 and 5 can employ the technical features of the electroabsorption modulator 100A of the first embodiment of Figs. 1 to 3 except for the reflection layer 260 have.

One of the problems of the embodiment is to improve the optical efficiency by improving the optical loss. To this end, the electroabsorption modulator 100B according to the first embodiment may include a reflection layer 260 for reflecting light to the active layer 123. [

The reflective layer 260 may be a DBR (Distribute Bragg Reflector) in which first and second layers having different refractive indices are alternately stacked one or more times.

The reflective layer 260 may include at least one of TiO 2, Si 3 N 4, ZrO 2, and TaBO 3 having a higher refractive index than the first layer, for example, a first layer comprising at least one of SiO 2 and MgF 2 having a lower refractive index than the second layer, But is not limited thereto.

The second embodiment can improve the capacitance increase of the optical modulation structure layer 120 of the reflection layer including the metal by arranging the reflection layer 260 of the DBR including the insulation layers.

The reflective layer 260 may be disposed on the optical modulation structure layer 120. The reflective layer 260 may extend to the upper edge region of the active layer 123. The width of the reflective layer 260 vertically overlapped with the active layer 123 may be 5 탆 to 6 탆. If the width of the reflective layer 260 vertically overlapped with the active layer 123 is less than 5 탆, peeling may occur at the end of the reflective layer 260 on the active layer 123. When the width of the reflective layer 260 vertically overlapped with the active layer 123 is more than 6 mu m, the area of the exit portion EA of the active layer 123 decreases and a part of the transmitted light can be reflected, It is possible to improve the reliability of the optical modulation due to the difference between the absorption and transmission of light.

The reflective layer 260 of the second embodiment extends to the edge region of the active layer 123 to improve the peeling of the reflective layer 160 and the light traveling in the outward and downward directions of the active layer 123 toward the active layer 123 So that the light loss can be improved.

In addition, the reflective layer 260 of the second embodiment can improve the capacitance increase caused in the reflective layer including the metal by the DBR including the insulating layers having different refractive indices. That is, the second embodiment can improve the reliability of the high-speed driving electro-absorption modulator 100B including the reflection layer 260 of the DBR.

Figures 6-11 disclose another embodiment of the first and second electrodes.

FIG. 6 is a plan view showing an electro-absorption modulator according to a third embodiment, and FIG. 7 is a cross-sectional view showing an electro-absorption modulator cut at C-C in FIG.

As shown in Figs. 6 and 7, the electro-absorption modulator 100C according to the third embodiment includes, except for the first and second electrodes 230 and 250, the first and second The technical features of the embodiment can be employed.

<First and Second Electrodes>

One of the problems of the embodiment is to realize a uniform electric field distribution and to improve the reliability of optical modulation. To this end, the electro-absorption modulator 100C according to the third embodiment may include the first and second electrodes 230 and 250. FIG. The first and second electrodes 230 and 250 of the third embodiment may be spaced apart from each other with the active layer 123 therebetween. In addition, one of the problems of the embodiment is to improve the absorption function by the electrode disposed on the active layer 123 at the time of transmission of light, thereby improving the modulation function. To this end, the second contact portion 251 disposed on the active layer 123 may include an area of 30% or less of the area of the active layer 123 above the active layer 123 in the electroabsorption modulator 100C according to the third embodiment. The electric field absorbing modulator 100C according to the third embodiment is arranged such that the second contact portion 251 having an area of 30% or less of the area of the upper surface of the active layer 123 is disposed to minimize the light absorbed by the electrode to improve the modulation function .

The first electrode 230 may be electrically connected to the first conductive semiconductor layer 121. The second electrode 250 may be electrically connected to the second conductive semiconductor layer 125.

The first electrode 230 may include a first electrode pad 233 and a first contact portion 231. The first electrode pad 233 may be spaced apart from the active layer 123 and the second electrode 250 by a predetermined distance. The first electrode pad 233 includes two first ends 233e-1 and 233e-1 symmetrically disposed in the first and second directions X and X 'with the second electrode 250 therebetween can do. The first ends 233e-1 and 233e-1 may be spaced apart from each other by the second electrode pad 253 of the second electrode 250 and two And may be disposed closest to each of the corners. The first electrode pad 233 may include a first side 233s surrounding the outer periphery 123s of the active layer 123. The radius of curvature of the first side 233s of the first electrode pad 230 may be greater than the radius of curvature of the outer circumference 123s of the active layer 123. [

The first contact portion 231 may be disposed in the first electrode pad 233. The first contact portion 231 may directly contact the first conductive semiconductor layer 121. The first contact portion 231 may be in contact with the upper surface of the first conductive type semiconductor layer 121 exposed from the reflective layer 260. The first contact portion 231 includes two second ends 231e-1 and 231e-1 symmetrical with each other in the first and second directions X and X 'with the second electrode 250 therebetween .

The first contact portions 231 may be separated from the first side portions 233s of the first electrode pad 230 by a predetermined distance. The first contact portions 231 may be spaced apart from the active layer 123 by a predetermined distance. The first contact portion 231 may have a structure that surrounds the outer circumference 123s of the active layer 123 by 2/3 or more. Accordingly, the first contact portion 231 can realize a uniform electric field as a whole in the active layer 123 having a circular top view. The first contact portion 231 may be spaced apart from the active layer 123 by a predetermined distance to improve current concentration concentrated at the shortest distance between the first contact portion 231 and the active layer 123.

The second electrode 250 may include a second electrode pad 253, a connection portion 255, and second and third contact portions 251a and 251b. The second electrode pad 253 may be spaced apart from the outside of the active layer 123 in the third direction Y. The second electrode pad 253 may include a width that increases as the distance from the active layer 123 increases, but the present invention is not limited thereto.

The second and third contact portions 251a and 251b may be disposed on the active layer 123. The second and third contact portions 251a and 251b may extend from one side of the active layer 123 to the central region. The second and third contact portions 251a and 251b may be overlapped with a portion of the active layer 123 in the vertical direction. The second contact portion 251a may be in direct contact with the upper edge region of the conductive layer 127. The second contact portion 251a may extend from the connection portion 255 and may be disposed in the second direction X '. The third contact portion 251b may extend from the second contact portion 251a and may correspond to a top view shape of the active layer 123. [ Accordingly, the third embodiment can realize a uniform electric field as a whole by the third contact portion 251b having a shape corresponding to that of the active layer 123.

For example, the third contact portion 251b may have a circular structure, but is not limited thereto. The third contact portion 251b may include a diameter W2 that is greater than the minor axis SA width W3 of the second contact portion 251a and the connecting portion 255. [

FIG. 8 is a plan view showing an electro-absorption modulator according to a fourth embodiment, and FIG. 9 is a cross-sectional view showing an electro-absorption modulator cut along a line D-D in FIG.

8 and 9, the electroabsorption modulator 100D according to the fourth embodiment may employ the technical features of the embodiment of Figs. 1 to 7, except for the second electrode 350. Fig.

<Second electrode>

One of the problems of the embodiment is to realize a uniform electric field distribution and to improve the reliability of optical modulation. To this end, the electroabsorption modulator 100D according to the fourth embodiment may include first and second electrodes 230 and 350. The first and second electrodes 230 and 350 of the fourth embodiment may be spaced apart from each other with the active layer 123 therebetween. In addition, one of the problems of the embodiment is to improve the absorption function by the electrode disposed on the active layer 123 at the time of transmission of light, thereby improving the modulation function. To this end, the electroabsorption modulator 100D according to the fourth embodiment may include an area of 30% or less of the area of the upper surface of the active layer 123, where the second contact portion 351 disposed on the active layer 123 is. The electroabsorption modulator 100D according to the fourth embodiment is provided with a second contact portion 351 having an area of 30% or less of the area of the active layer 123 to minimize the light absorbed by the electrode to improve the modulation function . The first electrode 230 may employ the technical features of the electroabsorption modulator 100C according to the third embodiment of FIG. 6 and FIG.

The second electrode 350 may include a second electrode pad 353 and a second contact portion 351. The second electrode pad 353 may be spaced apart from the outside of the active layer 123 in the third direction Y. The second electrode pad 353 may include a width that increases as the distance from the active layer 123 increases, but the present invention is not limited thereto. The second electrode 350 may include a first connection portion 355 connecting the second electrode pad 353 and the second contact portion 351.

The second contact portion 351 may be disposed on the active layer 123 and may overlap the edge region of the active layer 123 in the vertical direction. The second contact portion 351 may directly contact the upper edge region of the conductive layer 127. The second contact portion 351 may include two third ends 351e-1 symmetrical in the first and second directions X and X 'from the first connection portion 355. The second contact portion 351 may include a second side portion 351s. The second side 351s may face the first side 233s of the first electrode pad 230. The radius of curvature of the second side portion 351s may be smaller than the radius of curvature of the first side portion 233s.

The second contact portion 351 overlaps with a part of the emission portion EA of the active layer 123 and is disposed in the edge region of the active layer 123 to minimize the absorption of light. For example, the first width from the second side 351s of the second contact portion 351 to the outside of the active layer 123 may be 20 占 퐉 or less. When the first width is more than 20 mu m, the modulation reliability may be degraded due to absorption of light by absorbing light concentrated at the center of the active layer 123. [

FIG. 10 is a plan view showing an electro-absorption modulator according to a fifth embodiment, and FIG. 11 is a cross-sectional view showing an electro-absorption modulator cut along a line E-E in FIG.

As shown in Figs. 10 and 11, the electro-absorption modulator 100E according to the fifth embodiment can employ the technical features of the embodiment of Figs. 1 to 9, except for the second electrode 350. [

<Second electrode>

One of the problems of the embodiment is to realize a uniform electric field distribution and to improve the reliability of optical modulation. To this end, the electroabsorption modulator 100E according to the fifth embodiment may include first and second electrodes 230 and 450. The first and second electrodes 230 and 450 of the fifth embodiment may be spaced apart from each other with the active layer 123 therebetween. In addition, one of the problems of the embodiment is to improve the absorption function by the electrode disposed on the active layer 123 at the time of transmission of light, thereby improving the modulation function. To this end, the electroabsorption modulator 100E according to the fifth embodiment may include an area of 30% or less of the area of the upper surface of the active layer 123, where the second contact portion 451 disposed on the active layer 123 is. The electroabsorption modulator 100E according to the fifth embodiment is provided with a second contact portion 451 having an area of 30% or less of the area of the upper surface of the active layer 123 to minimize the light absorbed by the electrode to improve the modulation function . The first electrode 230 may employ the technical features of the electroabsorption modulators 100C and 100D according to the third and fourth embodiments of FIGS. 6 to 9.

The second electrode 450 may include a second electrode pad 453 and a second contact portion 451. The second electrode pad 453 may be spaced apart from the outside of the active layer 123 in the third direction Y. The second electrode pad 453 may include a width that increases as the distance from the active layer 123 increases, but the present invention is not limited thereto. The second electrode 450 may include a first connection part 455 connecting the second electrode pad 453 and the second contact part 451.

The second contact portion 451 may be disposed on the active layer 123 and may overlap the edge region of the active layer 123 in the vertical direction. The second contact portion 451 may directly contact the upper edge region of the conductive layer 127. The second contact portion 451 may be spaced from the outer periphery of the active layer 123 along the upper edge region of the active layer 123. The top view of the second contact portion 451 may be in the form of a closed ring. The second contact portion 451 may include an inner portion 451i and an outer portion 451o. The inner side 451i may include a radius of curvature that is less than the outer side 451o. In the electric field absorbing modulator 100E according to the fifth embodiment, the ring-shaped second contact portion 451 is disposed at the edge region of the exit portion EA of the active layer 123, so that absorption of light can be minimized. For example, the width between the inside 451i of the second contact portion 451 and the outside circumference 123s of the active layer may be 20 占 퐉 or less. Accordingly, in the electric field absorbing modulator 100E according to the fifth embodiment, the ring-shaped second contact portion 451 is disposed at the edge region of the output portion EA of the active layer 123, so that the absorption of light can be minimized. When the first width is more than 20 mu m, the modulation reliability may be degraded due to absorption of light by absorbing light concentrated at the center of the active layer 123. [

12 is a cross-sectional view showing an electro-absorption modulator according to a sixth embodiment.

As shown in Fig. 12, the electro-absorption modulator 100F according to the sixth embodiment has a configuration in which at least one of the embodiments of Figs. 1 to 11 Feature can be adopted.

In addition, one of the problems of the embodiment is to realize high-speed communication of 10 Gbps or more at 100 m or less. For this, in the embodiment, the light emitting portion EA of the nitride-based semiconductor and the nitride-based optical modulating portion AP are integrated between the substrate 110, thereby reducing optical loss and realizing high-speed communication.

The light modulating part AP may be disposed on one side of the substrate 110 and the light emitting part EP may be disposed on the other side of the substrate 110. [ The light modulating unit AP and the light emitting unit EP may face each other in the vertical direction with the substrate 110 interposed therebetween. The light modulating unit AP and the light emitting unit EP may be formed on the substrate 110 by chemical or physical vapor deposition methods such as chemical vapor deposition (CVD) or molecular beam epitaxy (MBE) or sputtering or hydroxide vapor phase epitaxy (HVPE), or the like, but the present invention is not limited thereto. The light modulator AP may include a bandgap for modulating light provided from the light emitting unit EP. For example, the bandgap of the optical modulator AP may be equal to or smaller than the bandgap of the light emitting unit EP.

&Lt; Light emitting portion &

The light emitting unit EP may include a light emitting structure layer 170, first and second electrodes 191 and 193. The light emitting unit RP has a flip chip structure in which first and second electrodes 191 and 193 are disposed at a lower portion thereof.

The light emitting structure layer 170 includes a first semiconductor layer 171 on the other surface of the substrate 110, a light emitting layer 173 on the first semiconductor layer 171, a second semiconductor layer 173 on the light emitting layer 173, (175). Here, a plurality of protrusions 110r may be formed on the other surface of the substrate 110, and each of the plurality of protrusions 110r may include at least one of a hemispherical shape, a polygonal shape, and an elliptical shape, Or in the form of a matrix. The plurality of protrusions 110r may refract light incident from the lower surface of the substrate 110 to improve light efficiency incident on the optical modulator AP.

The first semiconductor layer 171 may be formed of at least one of Group III-V-VI or Group V-VI compound semiconductors. The first semiconductor layer 171 is formed of a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + y? . The first semiconductor layer 171 may include at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP and AlGaInP. The first semiconductor layer 171 may be an n-type semiconductor layer doped with an n-type dopant such as Si, Ge, Sn, Se, or Te.

The light emitting layer 173 may be at least one of a single well, a single quantum well, a multiple well, a multi quantum well (MQW), a quantum-wire structure, or a quantum dot structure have. The light emitting layer 173 may be formed by combining electrons (or holes) injected through the first semiconductor layer 171 and holes (or electrons) injected through the second semiconductor layer 175 into each other to form a light emitting layer 173 Which is a layer that emits light due to a difference in band gap according to the wavelength. The light emitting layer 173 may be formed of a compound semiconductor. The light emitting layer 173 may be formed of at least one of Group 3-Group-5 or Group-6-Group compound semiconductors. The light emitting layer 173 may include a plurality of alternately arranged well layers and a plurality of barrier layers. InGaN / AlGaN, InGaN / AlGaN, InGaN / InGaN, AlGaAs / GaAs, InGaAs / GaAs, InGaP / AlInGaP, InGaN / GaN, InGaP, or a pair of InP / GaAs.

The second semiconductor layer 175 may be formed of at least one of Group 3-Group-5 or Group-6-Group compound semiconductors. The second semiconductor layer 175 is formed of a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + y? . The second semiconductor layer 175 may include at least one of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP and AlGaInP. The second semiconductor layer 175 may be a p-type semiconductor layer doped with a p-type dopant such as Mg, Zn, Ca, Sr, or Ba. The second semiconductor layer 175 may be a single layer or a multilayer. The second semiconductor layer 175 may have a superlattice structure in which at least two different layers are alternately arranged.

<Contact layer>

The light emitting unit EP may include a contact layer 192 for electrically connecting the first semiconductor layer 171 and the first electrode 191. The contact layer 191 may be connected to the first semiconductor layer 171 exposed through the light emitting layer 173 and the second semiconductor layer 175. The contact layer 192 may be formed on the first semiconductor layer 171 and the second semiconductor layer 171 through a plurality of holes that pass through the light emitting layer 173 and the second semiconductor layer 175 to expose a portion of the first semiconductor layer 171, And can be electrically connected.

The upper surface of the contact layer 192 of the embodiment may be disposed higher than the active layer 173 and the lower surface of the contact layer 192 may be disposed below the light emitting structure layer 170. The contact layer 192 may be formed of a conductive metal material or a semiconductor material. For example, the contact layer 192 may include at least one of Ti, Cr, Ta, Al, Pd, Pt, Cu, Ni, Ag, Mo, Al, Au, Nb, . Also, the contact layer 192 may be formed of a semiconductor layer having a composition formula of In _x Al _y Ga _{1 -xy} N (0? X? 1, 0? _Y? 1, 0? _X + y? 1) . For example, the contact layer 192 may be a Group III-V or Group II-VI compound semiconductor such as GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, AlGaInP And the like.

&Lt; Insulating layer &

The light emitting portion EP may include an insulating layer 180 disposed on the light emitting structure layer 170. The insulating layer 180 may electrically isolate the contact layer 192 from the light emitting layer 173 and the second semiconductor layer 175. For this, the insulating layer 180 may be disposed on the light emitting structure layer 170 surrounding a plurality of holes that expose the first semiconductor layer 171. The insulating layer 180 may expose a portion of the second semiconductor layer 175. The second semiconductor layer 175 exposed from the insulating layer 180 may be in direct contact with the second electrode 193 have. The insulating layer 180 may be formed of a material selected from SiO ₂ , SiO _x , SiO _x N _y , Si ₃ N ₄ , Al ₂ O ₃ , and TiO ₂ .

<Reflective Layer>

The light emitting portion EP may include a reflective layer 181 disposed on the light emitting structure layer 170. The reflective layer 181 may be disposed between the second semiconductor layer 175 and the insulating layer 180, but is not limited thereto. The reflective layer 181 may be disposed on the contact layer 192 and may reflect light from the light emitting structure layer 170 toward the optical modulator AP. The reflective layer 181 may improve light efficiency by reflecting light that is absorbed by the first and second electrodes 191 and 193 or is lost to the outside as it proceeds downward of the light emitting portion EP.

The reflective layer 181 may include a metal or a layer selected from the group consisting of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf, But it is not limited thereto. For example, the reflective layer 181 may be a DBR in which first and second layers having different refractive indices are alternately stacked one or more times.

<First and Second Electrodes>

The first and second electrodes 191 and 193 may be disposed on the light emitting structure layer 170. The first electrode 191 may be electrically connected to the first semiconductor layer 171 and the second electrode 193 may be electrically connected to the second semiconductor layer 175.

The first and second electrodes 191 and 193 may be formed of a material selected from the group consisting of Ti, Ru, Rh, Ir, Mg, Zn, Al, In, Ta, Pd, Co, Ni, Si, &Lt; / RTI &gt;

The electric field absorbing modulator 100F according to the sixth embodiment is constructed such that the light emitting portion EA of the nitride based semiconductor and the nitride based light modulating portion AP are vertically integrated between the substrates 110 to reduce optical loss, Can be implemented.

13 is a cross-sectional view showing an electro-absorption modulator according to a seventh embodiment.

13, the electroabsorption modulator 100G according to the seventh embodiment employs the technical features of the electroabsorption modulator 100F according to the sixth embodiment of Fig. 12 except for the reflection part 500 .

One of the problems of the embodiment is that high-speed communication of 10 Gbps or more can be realized at 100 m or less. For this, in the embodiment, the light emitting portion EA of the nitride-based semiconductor and the nitride-based optical modulating portion AP are integrated between the substrate 110, thereby reducing optical loss and realizing high-speed communication. In addition, the electro-absorption modulator 100F according to the seventh embodiment may include a reflector 500 to reduce light loss.

The reflective portion 500 may be disposed on an outer surface of the substrate 110. The reflective portion 500 may be disposed on the outer surface of the light modulating portion AP and the light emitting portion EP. The reflective portion 500 may be configured to surround the outer surface of the substrate 110, the light modulator AP, and the light emitting portion EP.

The reflective portion 500 may include an insulating material and a reflective material. The reflector 500 may be at least one of PPA (Polyphthalamide), PCT (Poly-cyclohexylene Dimethyl Terephthalate), white silicone, and white EMC (Epoxy Molding Compound) Not to be

14 is a diagram showing a configuration of an optical communication system according to an embodiment.

14, an optical communication system 10 according to an embodiment may include an electro-absorption modulator 100, a lens module 13, and an output waveguide 15.

The electroabsorption modulator 100 may include the technical features of the electroabsorption modulators 100F, 100G according to the sixth or seventh embodiment of Figures 12 and 13. [

The lens module 13 may be disposed between the electroabsorption modulator 100 and the output waveguide 15. The lens module 13 may include a function of providing an optical signal provided from the electroabsorption modulator 100 to the output waveguide 15.

The output waveguide 15 may output an optical signal provided through the lens module 13 to the outside. The output waveguide 15 may include a clad and a core and may be disposed in parallel with the lens module 13 and the electric field absorbing modulator 100 in the vertical direction.

The optical communication system 10 may include first to third cover portions 11A to 11C. The first to third cover portions 11A to 11C may cover the electro-absorption modulator 100, the lens module 13, and the output waveguide 15, respectively, but are not limited thereto.

The nitride-based semiconductor field-effect modulator 100 can be used for high-speed optical communication of 10 Gbps or less at 100 m or less, for example, for high-speed optical communication in a home network or automobile. The nitride-based semiconductor electro-absorption modulator can improve the manufacturing cost of a general laser diode and the problem of the alignment reliability of the laser diode and the optical modulator.

The features, structures, effects and the like described in the embodiments are included in at least one embodiment and are not necessarily limited to one embodiment. Furthermore, the features, structures, effects and the like illustrated in the embodiments can be combined and modified by other persons skilled in the art to which the embodiments belong. Accordingly, the contents of such combinations and modifications should be construed as being included in the scope of the embodiments.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. It can be seen that the modification and application of branches are possible. For example, each component specifically shown in the embodiments can be modified and implemented. And that such variations and applications are to be construed as being included within the scope of the embodiments set forth in the appended claims

100: electric field absorption modulator
AP: optical modulation unit
EP:
130, 230: first electrode
150 to 450: second electrode
160, 260: reflective layer
500:

Claims (17)

A first conductive semiconductor layer;
An active layer on the first conductive semiconductor layer;
A second conductive semiconductor layer on the active layer;
A first electrode disposed on the first conductive type semiconductor layer and including a first contact portion in contact with the first conductive type semiconductor layer; And
And a second electrode disposed on the second conductive type semiconductor layer and spaced apart from the first electrode,
The second electrode includes a second contact portion disposed on the active layer and in contact with the second conductivity type semiconductor layer,
And the area of the second contact portion is 30% or less of the area of the active layer.
The method according to claim 1,
A second electrode pad spaced apart from the active layer; And a connection portion connecting the second electrode pad and the second contact portion.
3. The method of claim 2,
The second contact portion overlaps with a part of the edge region of the active layer,
Wherein the second contact portion has a horseshoe shape including two ends that are symmetrical in the first direction from the connecting portion.
The method according to claim 1,
The second contact portion includes a first side facing the second electrode pad and a second side disposed on the opposite side of the first side,
And the width between the second side portion and the outside of the active layer is 20 占 퐉 or less.
The method according to claim 1,
The top view of the second contact portion is overlapped with the edge region of the active layer in the form of a closed ring,
Wherein the second contact portion includes inner and outer sides, and the width between the outer side and the outer side of the active layer is 20 占 퐉 or less.
3. The method of claim 2,
Wherein the second contact portion extends to the center portion of the active layer and the second contact portion includes a circular shape on the central portion and the width of the second contact portion on the central portion is larger than the width of the connection portion.
The method according to claim 1,
Wherein the first electrode and the first contact portion include two ends symmetrical in a first direction,
Wherein the first contact portion faces the outer periphery of the active layer by 2/3 or more.
The method according to claim 1,
And a third electrode that is symmetrical with the first electrode in the second direction with the active layer interposed therebetween, and the third electrode includes a third contact portion in contact with the first conductive type semiconductor layer.
9. The method of claim 8,
And a fourth electrode that is symmetrical with the second electrode in the first direction with the active layer interposed therebetween, and the fourth electrode includes a fourth contact portion that is in contact with the second conductive type semiconductor layer.
10. The method of claim 9,
The fourth electrode overlaps with a part of the edge region of the active layer,
And the fourth contact portion has a horseshoe shape including two ends that are symmetrical with respect to the second contact portion in the first direction.
The method according to claim 1,
And a reflective layer disposed on the first conductivity type semiconductor layer and extending to an edge region of the active layer,
Wherein the reflective layer comprises a multilayer structure including a metal layer and an insulating layer, and a DBR (Distribute Bragg Reflector).
12. The method of claim 11,
Wherein the reflective layer includes an overlap region vertically overlapped with the active layer,
Wherein the overlap region is 5 占 퐉 to 6 占 퐉.
The method according to claim 1,
The top view of the active layer has a circular phenomenon, and the area of the active layer is 5% or less of the area of the second conductivity type semiconductor layer.
The method according to claim 1,
A substrate in contact with the first conductive type semiconductor layer;
And a nitride based light emitting structure layer disposed on the opposite side of the first conductive type semiconductor layer and in contact with the substrate.
15. The method of claim 14,
Wherein the light emitting structure layer includes a first semiconductor layer, a light emitting layer on the first semiconductor layer, and a second semiconductor layer on the light emitting layer,
A fifth electrode disposed below the light emitting structure layer and electrically connected to the first semiconductor layer; and a sixth electrode electrically connected to the second semiconductor layer.
15. The method of claim 14,
And a reflective portion surrounding the first conductive semiconductor layer, the substrate, and the light emitting structure layer.
17. An electro-absorption modulator as claimed in any one of claims 1 to 16, And
And an output waveguide disposed on the electroabsorption modulator.

Images