30results about How to "Improve internal quantum efficiency" patented technology

The invention discloses a light-emitting diode epitaxial wafer and a preparation method thereof, and relates to the field of semiconductor photoelectric devices. The light-emitting diode epitaxial wafer sequentially comprises a substrate, a buffer layer, an N-type GaN layer, a multi-quantum well layer, an electron blocking layer and a P-type GaN layer. The buffer layer sequentially comprises a first AlN layer, a second AlN layer, a third AlN layer, a first superlattice layer, a first AlGaN layer, a second superlattice layer and a first GaN layer; the first superlattice layer comprises a fourth AlN layer and a second AlGaN layer which are alternately stacked, and the second superlattice layer comprises a third AlGaN layer and a second GaN layer which are alternately stacked; a first V-shaped pit extending to the second superlattice layer is formed in the third AlN layer, a second V-shaped pit is formed in the first superlattice layer, and the second V-shaped pit is filled and leveled up by the first AlGaN layer; the second superlattice layer forms a third V-shaped pit, and the first V-shaped pit and the third V-shaped pit are filled and leveled up by the first GaN layer. By implementing the invention, the luminous efficiency can be improved.

The invention provides an epitaxial structure, a manufacturing method and a chip structure. The epitaxial structure comprises a plurality of sub-active layers, wherein each sub active layer is doped with doping elements with different concentrations. As and / or Sb trace elements are doped into the active layer, so that the disorder degree of the active layer is improved, and the internal quantum efficiency and the luminous efficiency are improved. By adopting a segmented doping mode, the forbidden bandwidth difference caused by strain accumulation of quantum well layer materials at different positions is corrected, so that the light-emitting wavelength is more consistent, and the light-emitting efficiency is further improved.

The invention discloses a light-emitting diode, and the light-emitting diode comprises a semiconductor epitaxial lamination layer which is provided with a first surface and a second surface which are opposite to each other, and comprises a first type semiconductor layer, an active layer and a second type semiconductor layer which are sequentially stacked in the direction from the first surface to the second surface; a first spacing layer is arranged between the first type semiconductor layer and the active layer; a second spacing layer is arranged between the second type semiconductor layer and the active layer; the structure is characterized in that the second spacing layer is of a multi-layer structure formed by stacking sub-layers formed by two or more than two materials. According to the invention, the blocking effect of the second spacing layer on defects such as diffusion and dislocation of doped atoms can be enhanced, so that the thickness of the second spacing layer is reduced to the greatest extent, the radiation recombination proportion of carriers in the active layer is improved, and the internal quantum efficiency and ESD performance of the light-emitting diode are improved.

The invention relates to the technical field of semiconductor light emitting diodes, and discloses a composite patterned substrate and a preparation method thereof. The preparation method comprises the following steps: preparing a SiO2 film layer on a substrate; coining glue is prepared on the SiO2 film layer; transferring the pattern of the soft template to the SiO2 film layer by using a nanoimprint technology; performing etching treatment on the SiO2 film layer to form a graphic structure with a preset morphology, and etching to remove part of the substrate material to form a pit to obtain a patterned substrate; preparing an AlN layer on the substrate, filling the pit with the AlN layer, and covering the surface of the graphic structure; carrying out photoetching treatment and etching treatment on the AlN layer, so that the AlN layer is filled in the pit and covers the side surface of a part of the pattern structure; and carrying out annealing treatment, and removing the residual photoresist to obtain the composite patterned substrate. By implementing the preparation method provided by the invention, the obtained composite patterned substrate can improve the crystal quality of the epitaxial layer, thereby improving the internal quantum efficiency and final brightness of the chip.

This invention discloses an epitaxial wafer for a deep ultraviolet (UV) light-emitting diode (LED) and its fabrication method, relating to the field of semiconductor optoelectronic devices. The UV LED epitaxial wafer includes a substrate and a buffer layer, an N-type AlGaN layer, an active layer, an electron blocking layer, and a P-type AlGaN layer sequentially grown on the substrate. The active layer has a periodic structure, with each period comprising a sequentially stacked quantum well layer and a quantum barrier layer, and the number of periods in the active layer is ≥2. The quantum barrier layer comprises a sequentially stacked AlInGaN layer and a P-AlInGaN layer. Implementing this invention can effectively improve the luminous efficiency of deep ultraviolet LEDs.

The invention provides a micro light-emitting element and a micro light-emitting element structure. The micro light-emitting element comprises an epitaxial structure, a first electrode, a second electrode, a first contact layer and a diffusion structure. The epitaxial structure comprises a first type semiconductor layer, an active layer and a second type semiconductor layer which are stacked in sequence. The second type semiconductor layer has an outer surface relatively away from the first type semiconductor layer. The first and second electrodes are respectively disposed on the epitaxial structure and electrically connected to the first and second type semiconductor layers, respectively. The first contact layer is disposed between the first electrode and the first type semiconductor layer. The diffusion structure is disposed on a side of the second type semiconductor layer away from the first type semiconductor layer. The conductivity of the diffusion structure is smaller than that of the second type semiconductor layer. The outer surface of the second-type semiconductor layer exposes the lower surface of the diffusion structure away from the first-type semiconductor layer. According to the micro light-emitting element, the uniformity of the current density can be improved, so that the internal quantum efficiency is improved.

The present disclosure provides a photoelectric device based on enhanced photoelectric recycling effect, comprising: a substrate; a P-type electrode layer, which is located at one end of the substrate surface; a bottom battery layer, which is located at the other end of the substrate surface to be connected to the P-type electrode layer, and the bottom battery layer is used to absorb excitation light photons and convert them into electrons to achieve photoelectric-electro-optical conversion; a highly doped tunnel junction layer, which is located on the bottom battery and is used to provide a low-resistance and optically low-loss connection; a top battery layer, which is located on the highly doped tunnel junction layer and is used to absorb excitation light photons and convert them into electrons to achieve photoelectric conversion; wherein the energy band width of the top battery layer is greater than or equal to the energy band width of the bottom battery layer; an N-type electrode layer, which is located at one end of the surface of the top battery layer. The present disclosure also provides a method for preparing a photoelectric device based on enhanced photoelectric recycling effect and its application.

The invention discloses a light-emitting diode and a light-emitting device. A second semiconductor layer in the light-emitting diode is a P-type doped layer; wherein the second semiconductor layer at least comprises a P-type transition layer, a P-type space layer and a P-type limiting layer which are stacked in sequence, the P-type transition layer is located between the P-type space layer and the active layer, and the P-type space layer is located between the P-type transition layer and the P-type limiting layer. The P-type space layer and the P-type limiting layer are made of AlxGa (1-x) P materials, wherein x is larger than or equal to 0 and smaller than or equal to 1. The band gap of the AlGaP material ranges from 2.26 eV to 2.48 eV, and the band gap of the AlP is larger than that of the AlInP, the P-type space layer and the P-type limiting layer are arranged to be an AlGaP material system, so that the conduction band of the P-type semiconductor layer and the band order of the multi-quantum well light-emitting layer can be greatly improved, electron overflow can be greatly reduced, non-radiative recombination of electrons in the P-type semiconductor layer is blocked, and the light-emitting efficiency of the light-emitting device is improved. And the internal quantum efficiency and the HC performance of the LED are improved.

This invention discloses a white LED device and its preparation method, belonging to the field of white LED lighting technology. It solves the problems of existing technologies where a single phosphor cannot emit white light, two phosphors result in low luminous efficiency of white LED lamps, and three phosphors involve complex and costly encapsulation processes. The white LED device includes an ultraviolet LED chip and a phosphor layer disposed in the optical path of the ultraviolet LED chip; the phosphor layer contains a phosphor with the chemical composition shown in formula (1), K3YSi 2‑x Hf x O7:yEu 2+ (1), where x is the mole fraction of Hf, 2-x is the mole fraction of Si, and y is the mole fraction of Eu, wherein 0.01≤x<2 and 0.001≤y≤0.1. The phosphor in the phosphor layer of the white LED device of this invention has high internal quantum efficiency, resulting in a high color rendering index for the white LED device. The color temperature is adjustable while ensuring white light emission, high internal quantum efficiency, and a high color rendering index.

The ultraviolet laser with the superlattice structure comprises a substrate, a buffer layer, a lower limiting layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, an upper limiting layer, a hole injection layer and a P-type contact layer which are sequentially stacked from bottom to top, and a P-type electrode is arranged on the P-type contact layer; the N-type electrode is arranged on the lower limiting layer; wherein the upper waveguide layer comprises a first superlattice structure layer, and the first superlattice structure layer comprises a plurality of Ba1Alb1Inc1Ga1-a1-b1-c1N potential barrier layers and a plurality of Bu1Alv1Inw1Ga1-u1-v1-w1N potential well layers, and the Ba1Alb1Inc1Ga1-a1-b1-c1N potential barrier layers and the Bu1Alv1Inw1Ga1-u1-v1-w1N potential well layers are arranged alternately. According to the ultraviolet laser, the upper waveguide layer with the superlattice structure layer is introduced, electrons are effectively prevented from being leaked to the P side, the injection efficiency of carriers is improved, the internal quantum efficiency is improved, and therefore the performance of the ultraviolet laser is improved.

The invention discloses a gallium nitride-based red light emitting diode epitaxial structure and preparation and application thereof. The epitaxial structure sequentially comprises a sapphire substrate, a low-temperature GaN nucleating layer, a high-temperature non-doped GaN buffer layer, an n-type GaN layer, a low-temperature GaN V-type layer, an In < x > < 1 > Ga < 1-x > < 1 > N / GaN stress release layer, an In < x > Ga < 1-x > N / In < y > Ga < 1-y > N multi-quantum well light-emitting layer structure MQW, a composite protection layer, a p-type Al < y > < 1 > Ga-y < 1 > N electron barrier layer, a high-temperature p-type GaN layer and a p-type InGaN contact layer from bottom to top. The problem that the quantum efficiency of an existing InGaN-based red light LED is very low is solved. According to the invention, a composite protection layer with a stress release effect is grown between a high indium (In) component red light active region and a high-temperature p-type layer. Compared with an LED sample without a composite protection layer, the internal quantum efficiency is remarkably improved, and the maximum internal quantum efficiency is up to 110%.

The invention discloses a gallium nitride device and a preparation method thereof, and relates to the technical field of semiconductor devices. The gallium nitride device comprises a sapphire substrate, an AlN nucleating layer, an N-type AlGaN buffer layer, an intrinsic AlGaN active layer, an electron blocking layer and a P-type AlGaN layer which are sequentially stacked from bottom to top, a gradient doping edge stop layer is arranged on the edge of the P-type AlGaN layer, and meanwhile a bottom electrode in ohmic contact with the N-type AlGaN buffer layer and a top electrode in ohmic contact with the P-type AlGaN layer are formed respectively. According to the invention, by optimizing the structural design of the substrate, the nucleating layer, the buffer layer, the active layer, the electron blocking layer, the edge termination layer and the electrode, and combining with the seagull optimization algorithm to accurately regulate and control the preparation process parameters, the comprehensive improvement of the light extraction efficiency, the carrier recombination efficiency, the breakdown voltage and the long-term working stability is realized; and the photoelectric property and the reliability of the gallium nitride device are obviously enhanced.

The invention discloses an LED epitaxial wafer structure and a preparation method thereof, and relates to the technical field of semiconductor photoelectric devices. The LED epitaxial wafer structure comprises a substrate, a buffer layer, an N-type limiting layer, an N-type barrier layer, an active layer, a P-type barrier layer, a P-type limiting layer, a P-type window layer and a P-type contact layer, the active layer comprises GaInP quantum dot layers and barrier layers, wherein the GaInP quantum dot layers and the barrier layers are periodically and alternately stacked. The GaInP quantum dot layer contains GaInP quantum dots, the density of the GaInP quantum dots is 1 * 10 < 9 > / cm < 2 > to 1 * 10 < 11 > / cm < 2 >, and the diameter of the GaInP quantum dots is 5 nm to 40 nm. According to the invention, the dislocation density can be effectively reduced, and the carrier limiting capability is improved, so that the internal quantum efficiency is improved, and the luminous efficiency of an LED chip is finally improved.

The present disclosure discloses a method for preparing a light-emitting diode epitaxial wafer and an epitaxial wafer with improved internal quantum efficiency, and belongs to the field of light-emitting diode production. During the first stage of the growth of the InGaN well layer, the indium source flow rate is linearly increased to the first indium source threshold, and the gallium source is linearly reduced from the first gallium source threshold to the second gallium source threshold, so that an In source enriched region can be formed within the thickness of the thin InGaN well layer in a short time, thereby improving the light extraction efficiency of the multi-quantum well layer. The second stage of growth plays a role in transition and improving the crystal quality. In the third stage, the indium source remains unchanged while the gallium source increases linearly, and in the fourth stage, both the indium source and the flow rate are increased to improve the luminous efficiency. In the fifth and sixth stages, the enrichment of In is further reduced, thereby improving the overall quality. The changes in the enrichment degree of In in the six stages relieve the polarization electric field, increase the overlapping area of ​​the electron-hole wave function, and improve the internal quantum efficiency of the light-emitting diode.

The application provides a stress release layer, a preparation method thereof, an epitaxial wafer and an LED chip. The stress release layer comprises a superlattice structure formed by periodically laminating first sublayers and second sublayers. The first sublayer comprises an InGaN layer, and the first sublayer is a non-intentionally doped layer. The second sublayer comprises a GaN layer, and the GaN layer is doped with Zn. The application solves the problem that the traditional stress release layer cannot improve the low hole injection efficiency and uneven distribution, the low hole mobility in GaN, and the difficulty in uniformly injecting holes into multiple quantum wells, and the problem that the quantum well close to the P side is overloaded, thereby limiting the overall luminous efficiency.

This invention relates to the field of light-emitting diode (LED) technology, specifically to a high-efficiency LED and its fabrication method. The method includes sequentially growing an AlN buffer layer, an undoped GaN layer, an N-type GaN layer, a low-temperature stress relief layer, a multiple quantum well layer, a P-type semiconductor layer, and a P-type ohmic contact layer on a substrate. During the growth of the multiple quantum well layer, quantum well layers and quantum barrier layers are periodically and alternately grown. The quantum well layer is an InGaN layer, and the quantum barrier layer is a combined structure comprising a BInGaN layer-BGaN layer-BN layer-GaN layer. This invention reduces the probability of carriers undergoing non-radiative recombination at defects, thereby improving the luminous efficiency of the LED.

The invention discloses a high-power non-polar ultraviolet LED based on a transversely-growing AlGaN / GaN heterojunction and a method. The high-power non-polar ultraviolet LED comprises a diamond substrate, a non-polar GaN buffer layer, a transversely-growing periodic n-type AlGaN / GaN layer, a non-polar Al < x > Ga < 1-x > N / Al < y > Ga < 1-y > N multi-quantum well layer and a transversely-growing periodic p-type AlGaN / GaN layer from bottom to top. According to the invention, a plurality of conducting channels are established by transversely growing periodic AlGaN / GaN heterojunctions, the carrier injection efficiency in the quantum well is improved by using a polarization effect, meanwhile, non-polar AlGaN is adopted in the quantum well region, the influence that quantum limits the stark effect is overcome, and finally, the heat dissipation performance is enhanced by using the diamond substrate.

The invention relates to a light emitting diode structure and a manufacturing method. The solar cell comprises a substrate, a back reflector, a buffer layer, a first semiconductor layer, an active layer and a second semiconductor layer, a Mesa structure extending to the first semiconductor layer is arranged along the second semiconductor layer, and the Mesa structure comprises a step surface and a groove which enable part of the first semiconductor layer to be exposed; the transparent conducting layer is arranged on the second semiconductor layer; the current blocking layer comprises a first insulating layer I and a first insulating layer II; the first bonding pad partially penetrates through the transparent conductive layer and the first insulating layer and is respectively contacted with the transparent conductive layer, the first insulating layer and the second semiconductor layer, and the second bonding pad partially contacts with the bottom wall of the groove; the second insulating layer is at least partially arranged on the transparent conductive layer; and the plurality of micro-disc resonant cavity structures are distributed on the surface of the second insulating layer and are in contact with the surface of the transparent conductive layer through the micropores. By introducing the micro-disc resonant cavity structure, the optical coupling efficiency and the light extraction efficiency are remarkably improved.

The application discloses an epitaxial structure of a quantum well LED with a gradually changed In component GaN / InGaN quantum well, which comprises, from bottom to top, a substrate, an AlN buffer layer, an N-type GaN layer, a GaN / InGaN superlattice layer, a low-temperature GaN layer, an In component gradually changed GaN / InGaN quantum well layer, an EBL layer and a p-type GaN layer; the In component gradually changed GaN / InGaN quantum well layer comprises n quantum wells and n quantum barriers which are alternately arranged from bottom to top; from the first quantum well to the (n-1)th quantum well, the In component in the quantum well increases gradually; the In component in the nth quantum well is lower than that in the (n-1)th quantum well; when the In component in the xth quantum well exceeds 0.35, the corresponding xth quantum barrier is InGaN material; when the In component in the xth quantum well does not exceed 0.35, the corresponding xth quantum barrier is GaN material; wherein n is a natural number greater than zero, n>=x>0. The above scheme can grow an AlGaInN system LED with high quality and long wavelength, and the InGaN / GaN quantum well structure has high crystal quality.

Disclosed is a flip-chip light-emitting diode chip and a preparation method thereof, comprising: a substrate; an N-type semiconductor layer, located on the substrate; an active layer, located on the N-type semiconductor layer; a P-type semiconductor layer, located on the active layer; a current spreading layer, located on the P-type semiconductor layer; and a first insulating layer, a P electrode, and an N electrode, wherein a portion of the first insulating layer is located on the current spreading layer, and a portion passes through the current spreading layer, the P-type semiconductor layer, and the active layer, and contacts the N-type semiconductor layer; the first insulating layer has a first through hole and a second through hole, the first through hole is located on the current spreading layer, the current spreading layer is connected to the P electrode through the first through hole, the second through hole is located in a portion of the first insulating layer, and the N-type semiconductor layer is connected to the N electrode through the second through hole. The purpose of the present disclosure is to provide a flip-chip light-emitting diode chip with an array electrode structure, thereby increasing the light-emitting area of ​​the flip-chip light-emitting diode chip and effectively improving the light efficiency of the flip-chip light-emitting diode.

This invention proposes a gallium nitride-based semiconductor laser with a gradient peak rate electric field waveguide layer. The fitting curves of the In ion intensity distribution or In atom concentration distribution, the fitting curve of the peak rate electric field distribution, and the fitting curve of the saturated electron drift velocity distribution obtained from SIMS testing of the upper and lower waveguide layers with the gradient peak rate electric field all satisfy any one of the Logistic function, Logistic 5 function, or Nelder function, forming a high electric field barrier. Electrons transporting from the active region to the p-type layer must overcome this barrier height, suppressing electron leakage from the active region to the p-type layer. The low electric field matches the low-velocity transport of holes, avoiding enhanced hole scattering. High injection efficiency allows carriers in the active region to quickly reach the stimulated emission threshold. The saturated electron drift velocity gradually decreases from high to low, and the low saturated electron drift velocity on the active region side avoids punch-through leakage caused by high-speed electrons rushing through the active region.

The present invention provides a semiconductor epitaxial structure and a manufacturing method thereof, and an LED chip, comprising stacking an N-type semiconductor layer, a gate-eliminating layer, an active layer, and a P-type semiconductor layer in sequence on the surface of the substrate, and releasing excess electrons through epitaxial structure design, effectively improving electron concentration, increasing the probability of electron tunneling, improving crystal quality, and reducing the operating voltage of the LED, thereby improving the antistatic ability of the LED.

The utility model discloses a nitride semiconductor laser, which comprises a heat dissipation heat sink and a laser structure, and is characterized in that the laser structure comprises a first type waveguide layer, a quantum well layer and a second type waveguide layer which are stacked in sequence; wherein the first type is a P type, and the second type is an N type; or, the first type is an N type, and the second type is a P type; the doping concentration of the P-type waveguide layer is gradually changed along the growth direction of the device; the nitride semiconductor laser is obtained by growing and stripping on the gallium surface of the gallium nitride substrate. The gallium-based solar cell is obtained by growing and stripping on a gallium surface, thereby being beneficial to heat scattering and improving the high-power output performance of the device; and meanwhile, in cooperation with gradient doping of the P-type waveguide layer, penetration dislocation can be reduced through staged lattice matching.

The present invention relates to an organic electroluminescent compound, a light-emitting device and a consumer product. By including the organic electroluminescent compound according to the present disclosure, an organic electroluminescent device having improved driving voltage and / or current efficiency characteristics can be provided.

The invention discloses a compound containing carbazole and an organic electroluminescent device. The compound is formed by connecting two carbazoles, triazine and dibenzofuran in a specific manner. Heavy hydrogen (deuterium) is introduced into the traditional organic material of the same type. The introduction of deuterium improves the phase solubility of the material and the doping material, improves the interface stability, and thus greatly improves the luminous efficiency and stability of the device. At the same time, the introduction of deuterium enables the compound to be better matched with the doping material, further improving the life span and luminous efficiency of the device.

The application relates to the technical field of semiconductors, in particular to a vertical cavity surface emitting laser and a preparation method thereof. The laser comprises, from bottom to top, an n-face electrode layer, a substrate layer, a buffer layer, an n-DBR layer, an SiO2 insulating layer located at the outer periphery above the n-DBR layer, an n-lower oxidation limiting structure layer, a lower space layer, a quantum well active region, an upper space layer, a p-upper oxidation limiting structure layer, a p-DBR layer, a contact layer and a p-face electrode layer which are sequentially arranged in the center of the SiO2 insulating layer from bottom to top to form a cylindrical platform. By adopting the symmetrical oxidation limiting structure, more carriers are limited in the oxidation hole, the output power and the electro-optical conversion efficiency can be improved, and the number and distribution of transverse modes can be controlled.

The present invention provides an epitaxial structure with a quantum dot layer, a method for manufacturing the same, and a light-emitting diode chip. The quantum dot active layer is used as the active region. Since the quantum dot layer itself has a three-dimensional limiting effect on carriers, the light-emitting efficiency of the light-emitting diode chip can be improved, and a higher brightness can be achieved even at a low current. In addition, the present invention uses the quantum dot active layer as the active region, and there is no need to increase the Al component in order to obtain a shorter light-emitting wavelength, thereby ensuring that the internal quantum efficiency of the light-emitting diode chip is high. In addition, the present invention makes the In component of the non-doped layer larger than the In component of the N-type barrier layer, so that there is a large positive mismatch between the non-doped layer and the base material, which provides better conditions for the growth of the quantum dot layer, thereby improving the manufacturing quality of the light-emitting diode chip.

This invention discloses a phosphor, its preparation method, and its application, belonging to the field of white LED lighting technology. It solves the problems in existing technologies where a single phosphor cannot emit white light, two phosphors result in low luminous efficiency of white LED lamps, and the encapsulation process for three phosphors is complex and costly. The phosphor has the chemical composition shown in formula (1): K3YSi 2‑x Hf x O7:yEu 2+ (1), where x is the mole fraction of Hf, 2-x is the mole fraction of Si, and y is the mole fraction of Eu, wherein 0.01≤x<2, 0.001≤y≤0.1. The phosphor of the present invention has the characteristics of high internal quantum efficiency of light emission, and the white LED device prepared from this single phosphor has a high color rendering index. Under the premise of ensuring white light emission and high internal quantum efficiency and color rendering index, the color temperature can be adjusted.

This invention proposes a gallium nitride-based semiconductor laser with a graded thermal conductivity waveguide layer. By fitting the In ion intensity distribution or In atom concentration distribution, the transverse phonon velocity distribution, and the thermal conductivity distribution of the graded thermal conductivity upper and lower waveguide layers using SIMS testing, all of these curves satisfy the Stirling function or the LineMod function. The gradient of the transverse TA phonon velocity homogenizes phonon scattering in the lower waveguide layer, reduces thermally induced lattice distortion, avoids optical field mode distortion, and improves the optical field confinement factor. The gradient of the transverse phonon velocity homogenizes the temperature distribution in the upper waveguide layer, changing the thermal stress from concentrated to distributed, reducing phonon transport loss caused by interface scattering. It avoids the "bottleneck effect" of heat flow at the interface between the active region and the lower waveguide layer, further reducing the temperature coefficient of the threshold, accelerating heat flow to the substrate, and preventing thermal runaway caused by increased driving current after exceeding the threshold.

The present application relates to the technical field of semiconductor optoelectronics, in particular to a multi-active-region cascaded semiconductor laser. The multi-active-region cascaded semiconductor laser comprises: a plurality of cascaded active regions, wherein each cascaded active region comprises a plurality of active regions; and a tunnel junction, arranged on at least one side of the cascaded active region and electrically connected with the cascaded active region; wherein in the cascaded active region, at least one group of adjacent active regions are connected through a barrier layer. In this way, more active regions are added in the periodic gain structure, which improves the internal quantum efficiency of the device and also reduces the carrier density, thereby obtaining more gains. The barrier layer connection does not have the property of introducing a new pn junction, so the layer will not increase the turn-on voltage for device operation, and meanwhile the epitaxial growth is much simpler than that of the tunnel junction.