30results about How to "Improved current scaling performance" patented technology

The invention provides a strained superlattice tunnel junction ultraviolet LED (light emitting diode) epitaxial structure and a production method thereof. The epitaxial structure from top to bottom comprises: an epitaxial growth substrate, an AlN buffer layer, an n-type AlGaN layer, a multiple quantum wells, an electron blocking layer, a strained superlattice, an n-type degenerate doped AlGaN layer, and an n-type Si-doped AlGaN layer. The strained superlattice comprises a p-type AlGaN layer and an AlyGa1-yN / AlxGa1-xN. An AlGaN energy band, under effects of a polarized electric field, moves as a whole along a low energy direction. A superlattice structure contacts a heavily doped n-type AlGaN to form a p-AlGaN / SSL / n *-AlGaN tunnel junction. Electrons of a p-type AlGaN valence band, under effects of an external electric field, carried out tunneling through a tunnel effect to one side of the n-type AlGaN, and a hole is formed in the p-type AlGaN. The n-AlGaN is used as the cladding material instead of the p-type AlGaN, so that the problem of the p-type ohmic contact is avoided.

The invention discloses an LED chip and a preparation method thereof, and belongs to the technical field of semiconductors. The LED chip comprises a substrate, an undoped AlN buffer layer, an undoped GaN layer, an N-type GaN layer, a multi-quantum well layer, a P-type Al<y>Ga<1-y>N layer, a P-type GaN layer and a graphene film layer, wherein the undoped AlN buffer layer, the undoped GaN layer, the N-type GaN layer, the multi-quantum well layer, the P-type Al<y>Ga<1-y>N layer, the P-type GaN layer and the graphene film layer are sequentially stacked on the substrate; y is smaller than 0.5 and greater than 0.1; the multi-quantum well layer comprises an InGaN layer and a GaN layer which are alternately stacked; a groove which extends to the N-type GaN layer is formed in the graphene film layer; an N-type electrode is arranged on the N-type GaN layer; a P-type electrode is arranged on the graphene film layer; and multiple TiO2 nanorods are arranged on the graphene film layer in an array manner. The graphene film layer can be directly adopted as a seed layer through formation of the TiO2 nanorods, and the seed layer is tightly combined and is not easily destroyed, so that the light-emitting efficiency of an LED can be obviously improved.

The invention relates to an avalanche commutation diode special for a 16000A / 200-400V welding machine and a preparation method thereof. The invention solves the problems that an avalanche commutation diode special for a single welding machine has small capacity and that parallel connection and flow equalization are needed during the use of the avalanche commutation diode. An N-type (100) radial single crystal silicon piece, which has specific resistance Rho n of 5-10 Ohm-cm, diameter of 70 mm and thickness of 0.17-0.19 mm, is adopted; at the temperature of 1250 DEG C, double-surface once diffusion is carried out; the surface concentration of a surface higher-concentration region of a diffusion region is 0.06-n A, a junction depth X jP is 58-62 microns, and residual minority carrier lifetime Tao p of a base region is 9-13 Mu S; cathode-anode titanium-nickel-gold undergoes ohmic contact; a cathode table surface undergoes spray sand molding, corrosion, cleaning, passivation protection andintermediate test; and a shell is arranged, the thickness of a pipe is 5-6 mm, cold pressure welding packaging is conducted under the protection of nitrogen gas, and the thickness of the pipe is 5-6mm after the packaging. The avalanche commutation diode has stronger current expansion capability, larger capacity, better quality, higher reliability and lower use cost.

The invention provides a diode structure design with uniform luminous intensity. An epitaxial wafer structure comprises a substrate, an N-type layer, a multi-quantum well active region and a P-type layer from bottom to top; preparation of a chip technology is carried out; a current adjusting structure is arranged at the position, close to an N electrode, in the N-type layer; a resistance value of a region at the position, close to the N electrode, in the N-type layer is increased by the current adjusting structure; the current carrier aggregation effect of the position close to the N electrode is reduced by controlling the summarized occupied volume and the transverse and longitudinal etching depths of the current adjusting structure in the N-type layer; relatively multiple current carriers flow to the position close to a P electrode; the number of electrons which flow to the position close to the P electrode in the N-type layer is increased; different positions of a same LED chip are relatively uniform in light-emitting; and meanwhile, the current carrier aggregation effect is relieved, so that the reliability of an LED is further improved.

The present invention discloses a manufacture method of a light emitting diode having a high extension effect. The manufacture method comprises the following steps: providing an epitaxial substrate; growing the epitaxial layer of the light emitting diode through adoption of MOCVD; forming protection glue at the surface of the epitaxial layer of the light emitting diode, and performing alternate vacuum evaporation of a plurality of layers of Ni-Fe alloy membranes and Si3N4 membranes at two of four side faces of the epitaxial layer of the light emitting diode; performing alternate vacuum evaporation of a plurality of layers of Si3N4 membranes and Ni-Fe alloy membranes at the other two of four side faces of the epitaxial layer of the light emitting diode; and removing the protection glue at the surface of the epitaxial layer of the light emitting diode, exposing a p electrode and a n electrode, and forming an independent light emitting diode device through separation of epitaxial wafers. According to the invention, N-type and P-type current expansion of a light emitting diode is effectively enhanced without increasing the light blocking area of electrodes, and the N-type current expansion effect of a large-size chip is improved.

The invention discloses a large-power vertical structure LED epitaxial structure. The large-power vertical structure LED epitaxial structure includes a pre-paved Al layer, an AlN buffer layer, an AlGaN buffer layer, a u-type GaN layer, a first graphene layer, an n-type GaN layer, a multi-quantum well, a p-type GaN layer, and a second graphene layer, wherein all the above layers and the multi-quantum well are grown on an Si substrate; and the first graphene layer and the second graphene layer are formed by vapor deposition. The large-power vertical structure LED epitaxial structure has better photoelectric performance and has wide application.