semiconductor light-emitting devices

Abstract

A semiconductor light emitting device includes a first semiconductor layer on a substrate and having a first conductivity type; an active layer on the first semiconductor layer; a second semiconductor layer on the active layer and having a second conductivity type, the second semiconductor layer being doped with magnesium and having an upper surface substantially parallel to an upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate; and a third semiconductor layer on the second semiconductor layer and having the second conductivity type, the third semiconductor layer being doped with a magnesium concentration different from the magnesium concentration of the second semiconductor layer, and the third semiconductor layer having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] Korean Patent Application No. 10-2018-0119653, filed on October 8, 2018, with the Korean Intellectual Property Office (KIPO), and entitled “Semiconductor Light Emitting Device,” is incorporated herein by reference in its entirety. Technical Field

[0003] Example embodiments relate to a semiconductor light emitting device. Background Art

[0004] In a semiconductor light-emitting device, portions of an active layer comprising indium gallium nitride may have different indium concentrations, and light of different wavelengths may be generated in each portion depending on the amount of current passing through the active layer. Therefore, a method for manufacturing a light-emitting device that can efficiently generate light of a desired wavelength is needed. Summary of the Invention

[0005] According to example embodiments, a semiconductor light-emitting device is provided. The semiconductor light-emitting device may include: a first semiconductor layer on a substrate and having a first conductivity type; an active layer on the first semiconductor layer; a second semiconductor layer on the active layer and having a second conductivity type; and a third semiconductor layer on the second semiconductor layer and having the second conductivity type. The second semiconductor layer is doped with magnesium (Mg) and has an upper surface substantially parallel to an upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate. The third semiconductor layer may be doped with a magnesium concentration different from the magnesium (Mg) concentration of the second semiconductor layer, and the third semiconductor layer may have an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate.

[0006] According to example embodiments, a semiconductor light-emitting device is provided. The semiconductor light-emitting device may include a first semiconductor layer on a substrate and having a first conductivity type; an active layer on the first semiconductor layer; a second semiconductor layer on the active layer and having a second conductivity type; and a third semiconductor layer on the second semiconductor layer and having the second conductivity type. The second semiconductor layer includes a side portion having a first resistance and an upper portion having a second resistance lower than the first resistance, and the third semiconductor layer includes a side portion having a third resistance lower than the second resistance and an upper portion having a fourth resistance lower than the third resistance.

[0007] According to example embodiments, a semiconductor light emitting device is provided. The semiconductor light emitting device may include a first semiconductor light emitting unit on a substrate and a second semiconductor light emitting unit on the substrate and spaced apart from the first semiconductor light emitting unit. The first semiconductor light emitting unit may include: a first semiconductor layer having a first conductivity type; a first active layer on the first semiconductor layer; a second semiconductor layer on the first active layer and having a second conductivity type, the second semiconductor layer may be doped with magnesium (Mg) and may have an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate; and a third semiconductor layer on the second semiconductor layer and having the second conductivity type, the third semiconductor layer may be doped with a magnesium concentration different from the magnesium (Mg) concentration of the second semiconductor layer, and the third semiconductor layer may have an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate. The second semiconductor light emitting unit may include: a fourth semiconductor layer having the first conductivity type; a second active layer on the fourth semiconductor layer; a fifth semiconductor layer on the second active layer and having the second conductivity type, the fifth semiconductor layer may be doped with magnesium (Mg) and may have an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate; and a sixth semiconductor layer on the fifth semiconductor layer and having the second conductivity type, the sixth semiconductor layer may be doped with a magnesium (Mg) concentration different from the magnesium (Mg) concentration of the fifth semiconductor layer, and the sixth semiconductor layer may have an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate. In a plan view, the area of the first active layer in the first semiconductor light emitting unit may be smaller than the area of the second active layer in the second semiconductor light emitting unit, and the first semiconductor light emitting unit may generate light with a wavelength longer than that of the light generated by the second semiconductor light emitting unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Features will become apparent to those skilled in the art by describing in detail exemplary embodiments with reference to the accompanying drawings, in which:

[0009] Figures 1 to 4 Cross-sectional views illustrating stages in a method of manufacturing a semiconductor light emitting device according to example embodiments are shown.

[0010] Figure 5 A cross-sectional view of a semiconductor light emitting device according to example embodiments is shown.

[0011] Figure 6 A plan view of a semiconductor light emitting device according to example embodiments is shown. DETAILED DESCRIPTION

[0012] Hereinafter, a semiconductor light emitting device and a method of manufacturing the same according to example embodiments will be described more fully with reference to the accompanying drawings.

[0013] Figures 1 to 4 are cross-sectional views illustrating stages in a method of manufacturing a semiconductor light emitting device according to example embodiments.

[0014] Reference Figure 1 , a first semiconductor layer 110 may be formed on the substrate 100 , a mask 120 including an opening 130 may be formed on the first semiconductor layer 110 , and a second semiconductor layer 140 may be formed on an upper portion of the first semiconductor layer 110 exposed by the opening 130 .

[0015] The substrate 100 may include an insulating material (eg, glass, sapphire, etc.), a semiconductor material (eg, silicon (Si), silicon carbide (SiC), etc.), or a metal oxide (eg, zinc oxide (ZnO)).

[0016] The first semiconductor layer 110 may be deposited by metal organic chemical vapor deposition (MOCVD).

[0017] The first semiconductor layer 110 may be formed by a process such as a hydride vapor phase epitaxy (HVPE) process, a sputtering process, etc. In example embodiments, the first semiconductor layer 110 may include, for example, silicon (Si), germanium (Ge), selenium (Se), tellurium (Te), or carbon-doped gallium nitride (GaN), carbon-doped aluminum gallium nitride (AlGaN), carbon-doped indium gallium nitride (InGaN), etc. Therefore, the first semiconductor layer 110 may have n-type conductivity.

[0018] A buffer layer may be further formed between the substrate 100 and the first semiconductor layer 110 to alleviate lattice mismatch therebetween. The buffer layer may include, for example, gallium nitride (GaN).

[0019] The mask 120 may include an insulating material, such as silicon oxide, silicon nitride, etc. In a plan view, the opening 130 of the mask 120 may have, for example, a circular shape or a polygonal shape such as a hexagon.

[0020] In example embodiments, the second semiconductor layer 140 may be formed by a selective epitaxial growth (SEG) process using the upper portion of the first semiconductor layer 110 exposed by the opening 130 as a seed, and thus the second semiconductor layer 140 may include a material substantially the same as that of the first semiconductor layer 110. That is, the second semiconductor layer 140 may also include, for example, Si, Ge, Se, Te, or carbon-doped GaN, carbon-doped AlGaN, carbon-doped InGaN, etc., and thus may have n-type conductivity. When the second semiconductor layer 140 is grown from the first semiconductor layer 110, the first semiconductor layer 110 and the second semiconductor layer 140 may include substantially the same material to be bonded to each other, for example, to be integrated into a single seamless structure.

[0021] The second semiconductor layer 140 may be formed not only on the upper portion of the first semiconductor layer 110 exposed by the opening 130 but also on the upper portion of the mask 120 adjacent thereto, and may have, for example, a hexagonal pyramid shape. Therefore, the second semiconductor layer 140 may have an inclined side surface relative to the upper surface of the substrate 100.

[0022] Reference Figure 2 , an active layer 150 may be formed on the second semiconductor layer 140 . Next, a third semiconductor layer 160 may be formed on the active layer 150 . For example, the third semiconductor layer 160 may cover the entire exposed surface of the active layer 150 .

[0023] In example embodiments, the active layer 150 may include indium gallium nitride (InGaN) and may have a quantum well (QW) structure. The active layer 150 may be conformally formed on the second semiconductor layer 140 to have a constant thickness. For example, the active layer 150 may completely cover the inclined side surface of the second semiconductor layer 140.

[0024] In one embodiment, the indium concentration of the upper portion including the tip of the active layer 150 may be higher than the indium concentration of the other portions of the active layer 150. The indium concentration of the active layer 150 may vary according to the temperature during the process of forming the active layer 150. For example, when the active layer 150 is formed at a relatively low temperature, the active layer 150 may have a relatively high indium concentration. For example, the temperature during the formation of the active layer 150 may be adjusted so that the indium concentration in the tip of the active layer 150 is higher than the indium concentration in the other portions of the active layer 150.

[0025] The third semiconductor layer 160 may include, for example, Mg-doped GaN, Mg-doped AlGaN, Mg-doped InGaN, etc. Therefore, the third semiconductor layer 160 may have p-type conductivity.

[0026] The third semiconductor layer 160 may be formed on the exposed surface of the active layer 150 at a temperature of about 1000° C. or higher and a pressure of about 0.7 atm or higher. Therefore, for example, due to the content of magnesium doping and the high pressure, the third semiconductor layer 160 may be formed mainly in the horizontal direction (along the Figure 2 As a result, the third semiconductor layer 160 may be formed to have a thickness much greater in the horizontal direction (in the X direction) from the side surface of the active layer 150 than in the vertical direction (in the Y direction) from the tip of the active layer 150. Figure 2 As shown in the figure, the third semiconductor layer 160 may have an upper surface substantially parallel to the upper surface of the substrate 100 and an inclined side surface relative to the upper surface of the substrate 100, for example, the inclined side surface of the third semiconductor layer 160 may be parallel to the inclined side surface of the active layer 150.

[0027] In example embodiments, the third semiconductor layer 160 may include a side portion 160a and an upper portion 160b. Figure 2 As shown, the upper portion 160b may have an inverted triangle cross-section adjacent to the tip of the active layer 150, and the side portion 160a may have a parallelogram cross-section extending from one side of the inverted triangle along the inclined side surface of the active layer 150 to the mask 120. The upper surface of the upper portion 160b of the third semiconductor layer 160 may be parallel to the upper surface of the substrate 100.

[0028] In example embodiments, side portion 160a and upper portion 160b of third semiconductor layer 160 may have a first magnesium concentration and a second magnesium concentration, respectively. For example, due to the greater thickness of side portion 160a relative to upper portion 160b, the first magnesium concentration (in side portion 160a) may be lower than the second magnesium concentration (in upper portion 160b). Therefore, the resistance of side portion 160a of third semiconductor layer 160 may be greater than the resistance of upper portion 160b of third semiconductor layer 160.

[0029] Reference Figure 3A , the fourth semiconductor layer 170 may be formed on the third semiconductor layer 160. The fourth semiconductor layer 170 may include, for example, Mg-doped GaN, Mg-doped AlGaN, Mg-doped InGaN, etc., and thus may have p-type conductivity.

[0030] The fourth semiconductor layer 170 may be formed, for example, at a temperature of approximately 1000° C. and a pressure of approximately 0.7 atm. Therefore, for example, since the growth of the fourth semiconductor layer 170 has a lower pressure than the growth of the third semiconductor layer 160 , the fourth semiconductor layer 170 may be conformally grown on the third semiconductor layer 160 to a constant thickness.

[0031] In example embodiments, the fourth semiconductor layer 170 may include a side portion 170a and an upper portion 170b. Figure 3A As shown, the upper portion 170b of the fourth semiconductor layer 170 may have a trapezoidal cross-section, for example, the bottom base of the trapezoid directly located on the upper portion 160b of the third semiconductor layer 160 may be shorter in the horizontal direction than the top base of the trapezoid. Figure 3A As further shown in FIG, side portion 170a of fourth semiconductor layer 170 may also have a trapezoidal cross-section. The magnesium concentration of the entire fourth semiconductor layer 170 may be higher than that of the third semiconductor layer 160. For example, the magnesium concentration of any portion of the fourth semiconductor layer 170 may be higher than that of any portion of the third semiconductor layer. Therefore, the resistance of fourth semiconductor layer 170 may be lower than that of third semiconductor layer 160.

[0032] In example embodiments, the side portion 170a and the upper portion 170b of the fourth semiconductor layer 170 may have a third magnesium concentration and a fourth magnesium concentration, respectively. The third magnesium concentration (in the side portion 170a) may be lower than the fourth magnesium concentration (in the upper portion 170b).

[0033] In detail, the upper portion 170b of the fourth semiconductor layer 170 grown from the upper surface of the third semiconductor layer 160, for example, the upper portion 160b, may grow upward, for example, in a vertical direction substantially perpendicular to the upper surface of the substrate 100, and may be parallel to the upper surface of the substrate 100. The upper portion 170b of the fourth semiconductor layer 170 may be formed to have a magnesium (Mg) concentration greater than that of the side portions 170a of the fourth semiconductor layer 170, which grow from the inclined side surfaces of the third semiconductor layer 160 in a horizontal direction substantially parallel to the upper surface of the substrate 100. Therefore, the resistance of the upper portion 170b of the fourth semiconductor layer 170 may be lower than the resistance of the side portions 170a of the fourth semiconductor layer 170.

[0034] The second semiconductor layer 140, active layer 150, third semiconductor layer 160, and fourth semiconductor layer 170 sequentially stacked on the first semiconductor layer 110 of the substrate 100 may integrally form a semiconductor light emitting unit 180. The semiconductor light emitting unit 180 may have, for example, a hexagonal pyramid shape.

[0035] In another example, referring to Figure 3B , the thickness of the upper portion 170b of the fourth semiconductor layer 170 may be formed to be greater than the thickness of the side portion 170a of the fourth semiconductor layer 170. Therefore, the upper portion 170b of the fourth semiconductor layer 170 may have a rectangular cross-section.

[0036] Reference Figure 4, a portion of the mask 120 (e.g., outside the semiconductor light emitting unit 180) may be removed to expose the upper surface of the first semiconductor layer 110, and then the first electrode 190 may be formed on the exposed upper surface of the first semiconductor layer 110. The second electrode 200 may be formed on the fourth semiconductor layer 170 to complete the fabrication of the semiconductor light emitting device. For example, the second electrode 200 may be formed on the upper portion 170 b of the fourth semiconductor layer 170.

[0037] Specifically, the first electrode 190 may include a metal such as titanium (Ti) or gold (Au), and the second electrode 200 may include a metal such as nickel (Ni) or gold (Au). The first electrode 190 and the second electrode 200 may be connected to the n-type first semiconductor layer 110 and the p-type fourth semiconductor layer 170, respectively, to serve as an n-type electrode and a p-type electrode, respectively. A transparent electrode including, for example, indium tin oxide (ITO) may be further formed between the fourth semiconductor layer 170 and the second electrode 200.

[0038] The semiconductor light-emitting device manufactured by the above process may have the following features. The semiconductor light-emitting device may include a first semiconductor layer 110 and a second semiconductor layer 140 having a first conductivity type (i.e., n-type conductivity) on a substrate 100, an active layer 150 on the second semiconductor layer 140, a third semiconductor layer 160 having a second conductivity type (i.e., p-type conductivity) and doped with magnesium (Mg) on the active layer 150, a fourth semiconductor layer 170 having p-type conductivity and doped with magnesium at a different magnesium (Mg) concentration than the third semiconductor layer 160 on the third semiconductor layer 160, and a first electrode 190 and a second electrode 200. The upper surface of the third semiconductor layer 160 may be parallel to the upper surface of the substrate 100, the side surface of the third semiconductor layer 160 may be inclined relative to the upper surface of the substrate 100, the upper surface of the fourth semiconductor layer 170 may be parallel to the upper surface of the substrate 100, and the side surface of the fourth semiconductor layer 170 may be inclined relative to the upper surface of the substrate 100. The first electrode 190 may be located on the first semiconductor layer 110 , and the second electrode 200 may be located on the fourth semiconductor layer 170 .

[0039] The first semiconductor layer 110 and the second semiconductor layer 140 may be sequentially stacked on the substrate 100 to include the same material and may be bonded to each other. Therefore, the first semiconductor layer 110 and the second semiconductor layer 140 may be referred to as the lower portion and the upper portion of the first semiconductor layer 110, respectively. The first semiconductor layer 110 may be conformally formed on the substrate 100, and the second semiconductor layer 140 may have a hexagonal pyramid shape and thus may have a side surface inclined relative to the upper surface of the substrate 100. In example embodiments, each of the first semiconductor layer 110 and the second semiconductor layer 140 may include Si, Ge, Se, Te, or carbon-doped GaN.

[0040] The active layer 150 may be conformally formed on the second semiconductor layer 140 and may include InGaN. In one embodiment, the indium concentration of the upper portion of the active layer 150 may be higher than that of the lower portion of the active layer 150 , so that red light may be generated from the active layer 150 .

[0041] In example embodiments, each of the third semiconductor layer 160 and the fourth semiconductor layer 170 may include magnesium-doped GaN, magnesium-doped AlGaN, magnesium-doped InGaN, or the like, and may include side portions 160 a and 170 a, respectively, and upper portions 160 b and 170 b, respectively. The upper portion 160 b of the third semiconductor layer 160 may have an inverted triangular cross-section, and the upper portion 160 b of the fourth semiconductor layer 170 may have a trapezoidal cross-section or a rectangular cross-section.

[0042] In example embodiments, the magnesium concentration may have increasingly smaller values in the order of the upper portion 170b of the fourth semiconductor layer 170, the side portion 170a of the fourth semiconductor layer 170, the upper portion 160b of the third semiconductor layer, and the side portion 160a of the third semiconductor layer 160, and their resistances may have increasingly larger values in the order described above. In other words, the magnesium concentration may have a maximum value in the upper portion 170b of the fourth semiconductor layer 170, and may have decreasing values in the order of the upper portion 170b to the side portion 170a, the upper portion 160b of the third semiconductor layer 160, and the side portion 160a of the third semiconductor layer 160, and thus, may have increasing resistance values in the order of the upper portion 170b of the fourth semiconductor layer 170 to the side portion 170a, the upper portion 160b of the third semiconductor layer 160, and the side portion 160a of the third semiconductor layer 160.

[0043] Therefore, when a voltage is applied to each of the first electrode 190 and the second electrode 200, a current path can be formed to pass through (e.g., flow through) the upper portion 160b and the upper portion 170b of the third semiconductor layer 160 and the fourth semiconductor layer 170, respectively, which have relatively low resistance, the tip of the active layer 150 adjacent to the upper portion 160b and the upper portion 170b, and a portion of the second semiconductor layer 140 thereunder. Therefore, even if the respective portions of the active layer 150 where electrons and holes combine to generate light have different indium concentrations from each other, current can pass only through the upper portion of the active layer 150 (adjacent to the upper portion 160b and the upper portion 170b having relatively low resistance), for example, without passing through the lower portion of the active layer 150 adjacent to the side portions 160a and the side portions 170a, so that the wavelength of the generated light can be determined according to the indium concentration of the upper portion of the active layer 150, and light can be efficiently generated.

[0044] For example, when the upper portion of the active layer 150 has a relatively high indium concentration compared to other portions of the active layer 150, red light can be efficiently generated from the active layer 150. Conversely, when the upper portion of the active layer 150 has a relatively low indium concentration compared to other portions of the active layer 150, blue light can be efficiently generated from the active layer 150.

[0045] Figure 5 is a cross-sectional view showing a semiconductor light emitting device according to an example embodiment. In addition to the third semiconductor layer, Figure 5 The semiconductor light emitting device shown in FIG. Figure 4 The semiconductor light emitting devices described in the accompanying drawings are substantially the same or similar. Therefore, the same reference numerals denote the same elements, and detailed descriptions thereof are omitted herein.

[0046] Reference Figure 5 , the third semiconductor layer may include only the side portion 160a and may not include the upper portion. Figure 2 During the process described in , the third semiconductor layer is realized only with growth in the horizontal direction.

[0047] However, the third semiconductor layer may still have an upper surface parallel to the upper surface of the substrate 100, which can be achieved by forming the upper surface of the side portion 160a to be horizontal with respect to the upper surface of the substrate 100. Therefore, the upper portion 170b of the fourth semiconductor layer 170 on the upper surface of the third semiconductor layer may be formed to have a higher magnesium concentration than the side portion 170a of the fourth semiconductor layer 170.

[0048] Figure 6 is a plan view showing a semiconductor light emitting device according to an example embodiment. The semiconductor light emitting device includes Figure 4or Figure 5 Multiple semiconductor light-emitting units described in.

[0049] Reference Figure 6 The semiconductor light emitting device may include a first semiconductor layer 110 ( Figure 1 ) are formed on the first to third semiconductor light emitting units 182, 184, and 186 spaced apart from each other on the first semiconductor layer 110. That is, the first to third semiconductor light emitting units 182, 184, and 186 may be formed on portions of the first semiconductor layer 110 exposed by the first to third openings 132, 134, and 136 of the mask 120, respectively, and each of the first to third semiconductor light emitting units 182, 184, and 186 may have a hexagonal pyramid shape. In addition, an n-type electrode and a p-type electrode may be electrically connected to each of the first to third semiconductor light emitting units 182, 184, and 186 so that a voltage can be applied thereto.

[0050] In a plan view, the first semiconductor light emitting unit 182, the second semiconductor light emitting unit 184, and the third semiconductor light emitting unit 186 may have an increasingly larger area in this order. For example, the first to third semiconductor light emitting units 182 to 186 may have increasing area sizes in this order. Therefore, the first to third active layers included in the first, second, and third semiconductor light emitting units 182, 184, and 186, respectively, may have, for example, increasingly larger areas in this order, for example, increasing areas.

[0051] In an exemplary embodiment, light may be generated from the first to third active layers included in the first to third semiconductor light emitting units, respectively, to have successively shorter wavelengths, for example, decreasing wavelengths. In one embodiment, the first to third semiconductor light emitting units 182, 184, and 186 may generate, for example, red light, green light, and blue light, respectively. Thus, the semiconductor light emitting device including the first to third semiconductor light emitting units 182, 184, and 186 may emit white light.

[0052] The first to third semiconductor light emitting cells 182, 184, and 186 can be formed by forming first to third openings 132, 134, and 136 having different sizes in the mask 120 and performing an SEG process on portions of the first semiconductor layer 110 exposed by the first to third openings 132, 134, and 136. The first semiconductor light emitting cell 182 formed by the relatively small-sized first opening 132 can generate light with a longer wavelength than the third semiconductor light emitting cell 186 formed by the relatively large-sized third opening 136. In one embodiment, the first to third active layers respectively included in the first to third semiconductor light emitting cells 182, 184, and 186 can have increasingly larger thicknesses, e.g., increasing thicknesses, in this order.

[0053] In summary and review, the exemplary embodiments provide semiconductor light-emitting devices with improved characteristics. Specifically, in the semiconductor light-emitting devices according to the exemplary embodiments, although various portions of the active layer may have different indium concentrations, current can flow only through the upper portion of the active layer, thereby efficiently generating light having a desired wavelength. In other words, by configuring the p-type semiconductor layer formed on the active layer so that current flows only through a specific portion of the active layer, namely, the tip, light having a desired specific wavelength can be efficiently generated.

[0054] With respect to the above, a p-type second semiconductor layer that grows in a horizontal direction and has a first magnesium concentration can be formed on the active layer, which can be formed on an n-type first semiconductor layer having a hexagonal pyramid shape, and the second semiconductor layer can have an upper portion having a magnesium concentration greater than that of the side portion. The second semiconductor layer can also have a flat upper surface relative to the upper surface of the substrate. A p-type third semiconductor layer can be conformally formed on the second semiconductor layer, wherein the magnesium concentration of the upper portion formed on the upper surface of the second semiconductor layer can be greater than the magnesium concentration of the side portion formed on the side surface of the second semiconductor layer. Therefore, when a voltage is applied, current passes only through the second semiconductor layer having a relatively high magnesium concentration and the upper portion of the third semiconductor layer and the tip of the active layer formed thereunder, and light having a desired wavelength can be effectively generated regardless of the dispersion of the indium concentration of the active layer.

[0055] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and interpreted in a generic and descriptive sense only and not for purposes of limitation. In some cases, unless otherwise specifically noted, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, as would be apparent to one of ordinary skill in the art at the time of filing this application. Accordingly, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

Claims

1. A semiconductor light-emitting device, comprising: a first semiconductor layer on the substrate and having a first conductivity type; an active layer on the first semiconductor layer; a second semiconductor layer on the active layer and having a second conductivity type, the second semiconductor layer being doped with magnesium and having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate; as well as a third semiconductor layer on the second semiconductor layer and having the second conductivity type, the third semiconductor layer being doped with magnesium (Mg) at a concentration greater than that of the second semiconductor layer, and having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate, Wherein, the second semiconductor layer comprises: a side portion doped with a third concentration of magnesium; and an upper portion doped with magnesium at a fourth concentration greater than the third concentration, Wherein, the thickness of the side portion along the horizontal direction is greater than the thickness of the upper portion along the vertical direction.

2. The semiconductor light emitting device according to claim 1, wherein The third semiconductor layer includes: a side portion doped with a first concentration of magnesium; and An upper portion is doped with a second concentration of magnesium greater than the first concentration.

3. The semiconductor light emitting device according to claim 2, wherein An upper portion of the third semiconductor layer has a trapezoidal or rectangular cross section. The semiconductor light emitting device according to claim 1 , wherein: An upper portion of the second semiconductor layer has an inverted triangular cross-section. The semiconductor light emitting device according to claim 1 , wherein: The upper portion of the second semiconductor layer has a lower resistance than the side portion of the second semiconductor layer. The semiconductor light emitting device according to claim 1 , wherein: The active layer includes indium gallium nitride (InGaN).

7. The semiconductor light emitting device according to claim 6, wherein An indium concentration in an upper portion of the active layer is greater than an indium concentration in a lower portion of the active layer. The semiconductor light emitting device according to claim 7 , wherein: The active layer generates red light.

9. The semiconductor light emitting device according to claim 1, wherein The first semiconductor layer includes silicon (Si), germanium (Ge), selenium (Se), tellurium (Te) or carbon-doped gallium nitride (GaN), and each of the second semiconductor layer and the third semiconductor layer includes magnesium-doped gallium nitride (GaN) or magnesium-doped indium gallium nitride (InGaN).

10. The semiconductor light emitting device according to claim 1, wherein The first semiconductor layer includes: a lower portion on the substrate; and an upper portion on the lower portion of the first semiconductor layer and having a hexagonal pyramid shape, The active layer is conformally formed on an upper portion of the first semiconductor layer.

11. The semiconductor light emitting device according to claim 10, further comprising: a first electrode on a lower portion of the first semiconductor layer; as well as A second electrode is on the third semiconductor layer.

12. A semiconductor light emitting device comprising: a first semiconductor layer on the substrate and having a first conductivity type; an active layer on the first semiconductor layer; a second semiconductor layer on the active layer and having a second conductivity type, the second semiconductor layer comprising: a side portion having a first resistance, and an upper portion having a second resistance lower than the first resistance, wherein the thickness of the side portion along the horizontal direction is greater than the thickness of the upper portion along the vertical direction; and a third semiconductor layer on the second semiconductor layer and having the second conductivity type, the third semiconductor layer comprising: a side portion having a third resistance lower than the second resistance, and The upper portion has a fourth resistance lower than the third resistance.

13. The semiconductor light emitting device according to claim 12, further comprising: a first electrode connected to the first semiconductor layer; as well as a second electrode connected to the third semiconductor layer, Here, a current generated by applying a voltage to the first electrode and the second electrode flows through an upper portion of the second semiconductor layer and an upper portion of the third semiconductor layer and toward an upper portion of the active layer.

14. The semiconductor light emitting device according to claim 12, wherein: An upper portion and a side portion of each of the second semiconductor layer and the third semiconductor layer include magnesium (Mg), and An upper portion of the third semiconductor layer, a side portion of the third semiconductor layer, an upper portion of the second semiconductor layer, and a side portion of the second semiconductor layer have sequentially decreasing magnesium concentrations.

15. The semiconductor light emitting device according to claim 12, wherein: The second semiconductor layer includes an upper surface substantially parallel to an upper surface of the substrate, and An upper portion of the third semiconductor layer is located on an upper surface of the second semiconductor layer.

16. A semiconductor light emitting device comprising: A first semiconductor light emitting unit is on a substrate, wherein the first semiconductor light emitting unit comprises: a first semiconductor layer having a first conductivity type, a first active layer on the first semiconductor layer, a second semiconductor layer on the first active layer and having a second conductivity type, the second semiconductor layer being doped with magnesium (Mg), and having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate, and a third semiconductor layer on the second semiconductor layer and having the second conductivity type, the third semiconductor layer being doped with magnesium (Mg) at a concentration different from that of the second semiconductor layer, and having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate; and a second semiconductor light emitting unit on the substrate and spaced apart from the first semiconductor light emitting unit, the second semiconductor light emitting unit comprising: a fourth semiconductor layer having the first conductivity type, a second active layer on the fourth semiconductor layer, a fifth semiconductor layer on the second active layer and having the second conductivity type, the fifth semiconductor layer being doped with magnesium (Mg) and having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate, and a sixth semiconductor layer on the fifth semiconductor layer and having the second conductivity type, the sixth semiconductor layer being doped with magnesium (Mg) at a concentration different from that of the fifth semiconductor layer, and having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate, In a plan view, the area of the first active layer in the first semiconductor light emitting unit is smaller than the area of the second active layer in the second semiconductor light emitting unit, and the wavelength of light generated by the first semiconductor light emitting unit is longer than the wavelength of light generated by the second semiconductor light emitting unit.

17. The semiconductor light emitting device according to claim 16, further comprising: A third semiconductor light emitting unit is provided on the substrate, wherein the third semiconductor light emitting unit comprises: a seventh semiconductor layer having the first conductivity type, a third active layer on the seventh semiconductor layer, an eighth semiconductor layer on the second active layer and having the second conductivity type, the eighth semiconductor layer being doped with magnesium (Mg) and having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate, and a ninth semiconductor layer on the eighth semiconductor layer and having the second conductivity type, the ninth semiconductor layer being doped with magnesium (Mg) at a concentration different from that of the eighth semiconductor layer, and having an upper surface substantially parallel to the upper surface of the substrate and a side surface inclined relative to the upper surface of the substrate, In a plan view, an area of the second active layer in the second semiconductor light emitting unit is smaller than an area of the third active layer in the third semiconductor light emitting unit.

18. The semiconductor light emitting device according to claim 17, wherein The first to third semiconductor light emitting units generate red light, green light, and blue light, respectively.

Images