We report on the photoluminescent characteristics of InGaN/GaN multiple quantum well(MQW)nanorod arrays with high internal quantum efficiency.The InGaN/GaN MQWs are grown by metalorganic chemical vapor deposition on c...We report on the photoluminescent characteristics of InGaN/GaN multiple quantum well(MQW)nanorod arrays with high internal quantum efficiency.The InGaN/GaN MQWs are grown by metalorganic chemical vapor deposition on c-plane sapphire substrates,and then the MQW nanorod arrays are fabricated by using inductively coupled plasma etching with self-assembled Ni nanoparticle mask with low-damage etching technique.The typical diameter of the nanorods is from 200 nm to 300 nm and the length is around 800 nm,which almost is dislocation free.At room temperature,an enhancement of 3.1 times in total integrated photoluminescence intensity is achieved from the MQW nanorod arrays,in comparison to that of the as-grown MQW structure.Based on the temperature-dependent photoluminescence measurements,the internal quantum efficiency of the nanorod structure is 59.2%,i.e.,1.75 times of as-grown MQW structure(33.8%).Therefore,the nanorod structure with a significant reduction of defects can be a very promising candidate for highly efficient light emitting devices.展开更多
The influence of dry etching damage on the internal quantum efficiency of InGaN/GaN nanorod multiple quantum wells (MQWs) is studied.The samples were etched by inductively coupled plasma (ICP) etching via a selfassemb...The influence of dry etching damage on the internal quantum efficiency of InGaN/GaN nanorod multiple quantum wells (MQWs) is studied.The samples were etched by inductively coupled plasma (ICP) etching via a selfassembled nickel nanomask,and examined by room-temperature photoluminescence measurement.The key parameters in the etching process are rf power and ICP power.The internal quantum efficiency of nanorod MQWs shows a 5.6 times decrease substantially with the rf power increasing from 3W to 100W.However,it is slightly influenced by the ICP power,which shows 30% variation over a wide ICP power range between 30W and 600W.Under the optimized etching condition,the internal quantum efficiency of nanorod MQWs can be 40% that of the as-grown MQW sample,and the external quantum efficiency of nanorod MQWs can be about 4 times that of the as-grown one.展开更多
Roughened surfaces of light-emitting diodes(LEDs)provide substantial improvement in light extraction efficiency.By preparing the self-assemble nanoporous Ni template through rapid annealing of a thin Ni film,followed ...Roughened surfaces of light-emitting diodes(LEDs)provide substantial improvement in light extraction efficiency.By preparing the self-assemble nanoporous Ni template through rapid annealing of a thin Ni film,followed by a low damage dry etching process,a p-side-up LED with a roughened surface has been fabricated.Compared to a conventional LED with plane surface,the light output of LEDs with nanoporous p-GaN surface increases up to 71%and 36%at applied currents of 1 mA and 20 mA,respectively.Meanwhile,the electrical characteristics are not degraded obviously after surface roughening.展开更多
Three new indole alkaloids, flueindolines A–C(1–3), along with nine known alkaloids(4–12), were isolated from the fruits of Flueggea virosa(Roxb. ex Willd.) Voigt. Compounds 1 and 2 are two new fused tricyclic indo...Three new indole alkaloids, flueindolines A–C(1–3), along with nine known alkaloids(4–12), were isolated from the fruits of Flueggea virosa(Roxb. ex Willd.) Voigt. Compounds 1 and 2 are two new fused tricyclic indole alkaloids possessing an unusual pyrido[1, 2-a]indole framework, and 3 presents a rare spiro(pyrrolizidinyl-oxindole) backbone. Their structures with absolute configurations were elucidated by means of comprehensive spectroscopic analysis, chemical calculation, as well as X-ray crystallography. Chiral resolution and absolute configuration determination of the known compounds 4, 10, and 11 were reported for the first time. The hypothetical biogenetical pathways of 1–3 were herein also proposed.展开更多
基金Supported by the National Basic Research Program of China under Grant No 2011CB301900the National Natural Science Foundation of China under Grant Nos 61176063,60990311,60820106003,60906025,and 60936004+1 种基金the Natural Science Foundation of Jiangsu Province under Grant Nos BK2008019,BK2010385,BK2009255,and BK2010178the Research Funds from NJUYangzhou Institute of Optoelectronics.
文摘We report on the photoluminescent characteristics of InGaN/GaN multiple quantum well(MQW)nanorod arrays with high internal quantum efficiency.The InGaN/GaN MQWs are grown by metalorganic chemical vapor deposition on c-plane sapphire substrates,and then the MQW nanorod arrays are fabricated by using inductively coupled plasma etching with self-assembled Ni nanoparticle mask with low-damage etching technique.The typical diameter of the nanorods is from 200 nm to 300 nm and the length is around 800 nm,which almost is dislocation free.At room temperature,an enhancement of 3.1 times in total integrated photoluminescence intensity is achieved from the MQW nanorod arrays,in comparison to that of the as-grown MQW structure.Based on the temperature-dependent photoluminescence measurements,the internal quantum efficiency of the nanorod structure is 59.2%,i.e.,1.75 times of as-grown MQW structure(33.8%).Therefore,the nanorod structure with a significant reduction of defects can be a very promising candidate for highly efficient light emitting devices.
基金Supported by the National Basic Research Program of China under Grant No 2011CB301900the National Natural Science Foundation of China(61176063,60990311,60820106003,60906025,60936004)+1 种基金The Natural Science Foundation of Jiangsu Province(BK2008019,BK2010385,BK2009255,BK2010178)the Research Funds from NJU-Yangzhou Institute of Optoelectronics.
文摘The influence of dry etching damage on the internal quantum efficiency of InGaN/GaN nanorod multiple quantum wells (MQWs) is studied.The samples were etched by inductively coupled plasma (ICP) etching via a selfassembled nickel nanomask,and examined by room-temperature photoluminescence measurement.The key parameters in the etching process are rf power and ICP power.The internal quantum efficiency of nanorod MQWs shows a 5.6 times decrease substantially with the rf power increasing from 3W to 100W.However,it is slightly influenced by the ICP power,which shows 30% variation over a wide ICP power range between 30W and 600W.Under the optimized etching condition,the internal quantum efficiency of nanorod MQWs can be 40% that of the as-grown MQW sample,and the external quantum efficiency of nanorod MQWs can be about 4 times that of the as-grown one.
基金Supported by the National Basic Research Program of China(2011CB301900)the National Natural Science Foundation of China(61176063,60990311,60820106003,60906025,60936004)+1 种基金The Nature Science Foundation of Jiangsu Province(BK2008019,BK2010385,BK2009255,BK2010178)the Research Funds from NJU-Yangzhou Institute of Optoelectronics.
文摘Roughened surfaces of light-emitting diodes(LEDs)provide substantial improvement in light extraction efficiency.By preparing the self-assemble nanoporous Ni template through rapid annealing of a thin Ni film,followed by a low damage dry etching process,a p-side-up LED with a roughened surface has been fabricated.Compared to a conventional LED with plane surface,the light output of LEDs with nanoporous p-GaN surface increases up to 71%and 36%at applied currents of 1 mA and 20 mA,respectively.Meanwhile,the electrical characteristics are not degraded obviously after surface roughening.
基金the National Key R & D Program of China (No. 2018YFC1706200)the National Natural Science Foundation of China (Nos. 81630095, 81622045, and 81803379)+2 种基金the Science & Technology Program of China (No.2019ZX09735002-003)the China Postdoctoral Science Foundation(Nos. 2019T120794, and 2018M633291)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (No. 2017BT01Y036)。
文摘Three new indole alkaloids, flueindolines A–C(1–3), along with nine known alkaloids(4–12), were isolated from the fruits of Flueggea virosa(Roxb. ex Willd.) Voigt. Compounds 1 and 2 are two new fused tricyclic indole alkaloids possessing an unusual pyrido[1, 2-a]indole framework, and 3 presents a rare spiro(pyrrolizidinyl-oxindole) backbone. Their structures with absolute configurations were elucidated by means of comprehensive spectroscopic analysis, chemical calculation, as well as X-ray crystallography. Chiral resolution and absolute configuration determination of the known compounds 4, 10, and 11 were reported for the first time. The hypothetical biogenetical pathways of 1–3 were herein also proposed.
