13results about How to "Improve internal quantum efficiency" patented technology

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.

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 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.

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 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.

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 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 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.

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.