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Patent Issued for Nitride Semiconductor Light Emitting Device

February 19, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent by the inventors Shim, Hyun Wook (Gyeonggi-do, KR); Yoon, Suk Ho (Seoul, KR); Sakong, Tan (Gyeonggi-do, KR); Kim, Je Won (Seoul, KR); Kim, Ki Sung (Gyeonggi-do, KR), filed on April 6, 2012, was published online on February 4, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8643037 is assigned to Samsung Electronics Co., Ltd. (Suwon-Si, KR).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to a nitride semiconductor light emitting device.

"In recent years, a group III-V nitride semiconductor, such as a GaN semiconductor, has been prominent as an essential material for light emitting devices, such as light emitting diodes (LEDs), laser diodes (LDs), and the like, due to its excellent physical and chemical properties. LEDs or LDs using a group III-V nitride semiconductor material are mainly used in light emitting devices for producing light in a blue or green wavelength band. These light emitting devices are being used as light sources for various applications requiring high current and high output such as backlight units (BLUs), electronic display boards, lighting apparatuses and the like.

"With the use of a nitride semiconductor light emitting device in various applications, a method of effectively injecting electrons into an active layer has become important in a high-power light emitting device having a large area. According to the related art, a super lattice layer has been stacked for the diffusion of current into the active layer and for stress relief, and an electron ejection layer has been grown for electron injection. However, such a complex stack structure may increase stress and the possibility of occurrence of defects in an interface, and defects may be propagated to the active layer, whereby light emitting efficiency and reliability of the semiconductor light emitting device may be reduced."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "An aspect of the present invention provides a nitride semiconductor light emitting device being improved in current distribution due to two-dimensional electron gas (2DEG) and having an enhanced current injection effect and light emitting efficiency.

"An aspect of the present invention also provides a nitride semiconductor light emitting device having an electron injection layer relieving stress from a nitride layer and reducing the possibility of occurrence of defects.

"An aspect of the present invention also provides a nitride semiconductor light emitting device having superior luminance and being improved in productivity by simplifying a nitride semiconductor structure and reducing production time.

"According to an aspect of the present invention, there is provided a nitride semiconductor light emitting device including: n-type and p-type nitride semiconductor layers; an active layer disposed between the n-type and p-type nitride semiconductor layers; and an electron injection layer disposed between the n-type nitride semiconductor layer and the active layer, wherein the electron injection layer has a multilayer structure, in which three or more layers having different energy band gaps are stacked, the multilayer structure is repetitively stacked at least twice, and at least one layer among the three or more layers has a reduced energy band gap in individual multilayer structures in a direction toward the active layer.

"The multilayer structure may be formed of a semiconductor material having a composition expressed by In.sub.xAl.sub.yGa.sub.1-x-yN, where 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, and 0.ltoreq.x+y.ltoreq.1, and the multilayer structure may have different energy band gaps with different composition ratios of Al and In.

"The multilayer structure may be formed as a super lattice structure.

"The multilayer structure may include a laminate of InGaN/GaN/AlGaN layers.

"The multilayer structure may include a laminate of AlGaN/GaN/InGaN layers.

"The multilayer structure may include a laminate of InGaN/GaN/AlGaN/GaN layers.

"The multilayer structure may include a first layer, a second layer having a lower energy band gap than the first layer, and a third layer having an energy band gap between those of the first and second layers, and the first and second layers may be alternately stacked while having the third layer interposed therebetween.

"At least one of the first and second layers may have a reduced energy band gap in the individual multilayer structures in the direction toward the active layer.

"The third layer may include two or more layers having different energy band gaps, and the two or more layers may be stacked to be interposed between the first and second layers while allowing the energy band gaps thereof to be sequentially increased or decreased.

"The multilayer structure may include a first layer, a second layer having a lower energy band gap than the first layer, and a third layer having an energy band gap between those of the first and second layers, and the multilayer structure may have the first, third and second layers sequentially stacked therein.

"The multilayer structure may include a first layer, a second layer having a lower energy band gap than the first layer, and a third layer having an energy band gap between those of the first and second layers, and the multilayer structure may have the second, third and first layers sequentially stacked therein.

"A layer having the lowest energy band gap among the three or more layers may have an increased thickness in the individual multilayer structures in the direction toward the active layer.

"According to another aspect of the present invention, there is provided a nitride semiconductor light emitting device including: n-type and p-type nitride semiconductor layers; an active layer disposed between the n-type and p-type nitride semiconductor layers; and an electron injection layer disposed between the n-type nitride semiconductor layer and the active layer, wherein the electron injection layer has a multilayer structure, in which three or more layers having different energy band gaps are stacked, the multilayer structure is repetitively stacked at least twice, and a layer having the lowest energy band gap among the three or more layers has an increased thickness in individual multilayer structures in a direction toward the active layer.

"The multilayer structure may be formed of a semiconductor material having a composition expressed by In.sub.xAl.sub.yGa.sub.1-x-yN, where 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, and 0.ltoreq.x+y.ltoreq.1, and the multilayer structure may have different energy band gaps with different composition ratios of Al and In.

"The multilayer structure may be formed as a super lattice structure.

"The multilayer structure may include a first layer, a second layer having a lower energy band gap than the first layer, and a third layer having an energy band gap between those of the first and second layers, and the first and second layers may be alternately stacked while having the third layer interposed therebetween.

"At least one of the first and second layers may have a reduced energy band gap in the individual multilayer structures in the direction toward the active layer.

"The third layer may include two or more layers having different energy band gaps, and the two or more layers may be stacked to be interposed between the first and second layers while allowing the energy band gaps thereof to be sequentially increased or decreased.

"The multilayer structure may include a first layer, a second layer having a lower energy band gap than the first layer, and a third layer having an energy band gap between those of the first and second layers, and the multilayer structure may have the first, third and second layers sequentially stacked therein.

"The multilayer structure may include a first layer, a second layer having a lower energy band gap than the first layer, and a third layer having an energy band gap between those of the first and second layers, and the multilayer structure may have the second, third and first layers sequentially stacked therein."

URL and more information on this patent, see: Shim, Hyun Wook; Yoon, Suk Ho; Sakong, Tan; Kim, Je Won; Kim, Ki Sung. Nitride Semiconductor Light Emitting Device. U.S. Patent Number 8643037, filed April 6, 2012, and published online on February 4, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=72&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=3571&f=G&l=50&co1=AND&d=PTXT&s1=20140204.PD.&OS=ISD/20140204&RS=ISD/20140204

Keywords for this news article include: Semiconductor, Samsung Electronics Co. Ltd..

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Source: Electronics Newsweekly


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