5results about How to "Improve internal quantum efficiency" patented technology

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.

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.

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.

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.