Invented by Hyun-Soo Kim, Jae-hee Cho, Samsung Electronics Co Ltd
The Samsung Electronics Co Ltd invention works as followsA GaN-based composite semiconductor light emitting devices is provided. The semiconductor light-emitting device consists of a substrate, an n type semiconductor layer on it, an active layer on top of that, a p type semiconductor layer on top of that, a p electrode on the p semiconductor, an n electrode on a second area separated from the first of the layer of the semiconductor, a dielectric on one side of the stack, which includes the ntype layer, active layer and p semiconductor, a reflective on this dielectric, and a dielectric on
Background for GaN-based composite semiconductor light emitting devices
1. Field of the Disclosure
The disclosure is a GaN-based Group III-V compound light emitting semiconductor device and, more specifically, a flip-chip light emitting semiconductor device where a highly reflective layer is formed on the sidewall of an active GaN layer.
A semiconductor light-emitting diode is used widely in communication fields such as optical communications or in devices such as compact disc players (CDPs) or digital versatile disc players (DVDPs) as a way to transmit data or read and write data. A semiconductor LED can be used in a variety of applications, such as an outdoor electric sign with a large size or the backlighting for an LCD.
A GaN-based semiconductor LED is small, and consumes low power. A GaN-based semiconductor is particularly bright and has high light emission strength. It’s used for outdoor displays.
U.S. Pat. No. “6,630,689 describes a technique where a number of dielectric stacks is stacked on a wall mesa, and then a highly reflective coating layer is created, improving the efficiency of extracting light from an LED.
The present invention can provide a semiconductor device that emits light, but does not allow light to be emitted by a GaN sidewall including an active surface.
The present invention may also provide a device that emits light from a flip-chip device, which allows for improved light extraction.
According to one aspect of the invention, a semiconductor light-emitting device is provided, which includes: a substrate, an n type semiconductor layer on the substrate, an active layer on a region of the first n type semiconductor layer, a layer of p semiconductor on the active, a p electrode on the p semiconductor, an n electrode on a region that is separated from the region of first n semiconductor layer. A dielectric on a sidewall containing the active, p and n
The refractive index may range from 1 to 2.5.
The substrate can be made of transparent material (preferably sapphire).
The dielectric layer can be made of any of the following materials: silicon oxide, silicon dioxide, silicon nitride or silicon oxynitride; aluminum oxide; lithium fluoride and calcium fluoride.
The reflective layer can be made of any of the following materials: Ag, Al. Au, Pt. Ru and Ir.
The active layer and the p type semiconductor layer can be GaN-based III-V nitride compound.
The present invention is now described in reference to the drawings that accompany it, which show exemplary embodiments. The thickness of the layers and regions is exaggerated in the drawings to make it easier to understand.
FIG. FIG. 1 shows a schematic cross sectional view of an LED based on GaN in the group III-V semiconductors according to a particular embodiment of the invention. Referring to FIG. The LED of the present invention comprises a first compound-semiconductor layer 12 on a substrate transparent 10. The first compound layer 12 can be an n type group III-V semiconductor layer (for example, n GaN), or it may be another compound semiconductor. The first compound layer 12 can include a region R1 as well as a region R2. On a first region, R1, is stacked an active layer 14, from which light is emitted, such as blue light or UV ray, by recombination between p-type and non-p-type carriers. On the active layer 14, a second compound semiconductor layer 16, for example, p-GaN layer, is stacked. The second compound layer 16 can be a group III-V compound layer of p type, such as a GaN layer or another compound semiconductor. On the second region R2 of the first compound layer 16, an n-type electrolyte 30 is formed.
On the second compound-semiconductor layer 16, a p type electrode 20 is formed. The p type electrode 20 can include silver (Ag), or silver alloy.
A sidewall of a stack containing the p type GaN layer 16, active layer 14 and the n type GaN 12 forms an angle predetermined, for example approximately 35 to55 degrees, in relation to the substrate 10 On the sidewall, a highly-reflective 50 layer is formed. The highly-reflective 50 layer includes a dielectric 52 layer formed on sidewall 40, and a reflection layer 54 formed over the dielectric 52 layer. The reflective layer 54, which is a metallic coating, can be connected to either the p type electrode 20 or the n type electrode 30, but not both.
The transparent substrate 10 can be made of sapphire.Click here to view the patent on Google Patents.