共查询到20条相似文献,搜索用时 344 毫秒
1.
《Materials Letters》2003,57(24-25):3880-3883
Based on self-catalyzed vapor–liquid–solid mechanism, large-scale hexagonal GaN whiskers were synthesized via a two-step reaction of GaS powders with H2 and NH3 at 1000 °C. These whiskers were characterized using XRD, SEM, TEM, SAED, HRTEM, and Raman spectroscopy, in which the results obtained show that these GaN whiskers have the single crystal wurtzite structure with width of 20–200 nm and length of several micrometers. 相似文献
2.
Lundin W. V. Nikolaev A. E. Sakharov A. V. Zavarin E. E. Usov S. O. Sizov V. S. Zakgeim A. L. Chernyakov A. E. Tsatsul’nikov A. F. 《Technical Physics Letters》2010,36(11):1066-1068
A new method of forming the active region in high-efficiency InGaN/GaN/AlGaN light-emitting diode (LED) structure for long-wave
green range is described. The introduction of a short-period InGaN/GaN superlattice situated immediately under the emitting
quantum well and overgrown with GaN layer at reduced temperature leads to a more than tenfold increase in the efficiency of
emission. For the proposed LEDs, the maximum quantum efficiency was 12% at 552 nm and 8% at 560 nm. 相似文献
3.
北京大学物理系和介观物理国家重声、实验室MOCVD研究组采用一种改进的LP-MOCVD方法,在AI。O。衬底上生长了高质量的P型GaN和P型AIGaN,P型载流子浓度达2X10‘’cm-’,霍尔迁移率为30cm’/V.s。在此基础上,成功地研制出GaNP-N结和AIGaN/GaNrt异质结(DH)蓝光光发射二极管(LED)。皿一V族氯化物半导体材料(主要包括GaN、InN、AIN及其合金体系)广泛地应用于光电子和电子器件中。其中特别是蓝光到紫外波段的光发射器件,有着广泛的应用前景、巨大的市场需求以及深刻的物理意义,引起了人们极大地关注,成为目… 相似文献
4.
5.
7.
8.
GaN材料的GSMBE生长 总被引:2,自引:0,他引:2
在国内首次用NH3作氮源的GSMBE方法在α-Al2O3衬底上生长出了GaN单昌外延膜。GaN生长速率可达0.5μm/h。GaN外延膜的(0002)双晶X射线衍射峰回摆曲线的半高宽最窄为8arcmin。霍尔迁移率为50cm^2/V.s。对质量好的GaN膜,室温阴性发光谱上只有一个强而锐的近岸边发光峰,谱峰位于372nm处,谱峰半高宽为14nm(125meV)。 相似文献
9.
10.
Mao Yang Jun-jie Shi Min Zhang Shuai Zhang Zhi-qiang Bao Shao-jun Luo Tie-Cheng Zhou Tian-cong Zhu Xiang Li Jia Li 《Materials Chemistry and Physics》2013
Both the electronic structures and the optical properties of single-walled zigzag GaN nanotubes (NTs) with MgGa–ON co-doping are investigated using first-principles calculations. We find that the MgGa–ON defect complex can exist stably in GaN NTs. The direct band gap width of the GaN NTs can be reduced by means of the MgGa–ON co-doping. The electrons of the valence band maximum (VBM) state are localized around the N atoms bonded with the Mg atom. The imaginary part ε2 of the complex dielectric function of GaN NTs with MgGa–ON co-doping has a sharp peak closely related to the optical transitions between the VBM and conduction band minimum states. 相似文献
11.
对激光剥离Al2O3/GaN技术,建立了紫外脉冲激光辐照过程中GaN外延层内热传导理论模型。计算分析了不同能量密度脉冲激光辐照时,GaN外延层内的温度场分布,由此得到激光剥离的阈值条件。采用紫外KrF准分子激光器对Al2O3/GaN样品进行激光剥离实验,样品表面显微镜和端面扫描电镜(SEM)测试照片说明,计算结果与实验现象相符。进一步分析表明,脉冲激光的能量密度和频率是实现激光剥离的关键参数,适当选取这些参数能将GaN材料内的高温区控制在100nm以内,实现高效低损伤激光剥离。 相似文献
12.
《Vacuum》2012,86(2):201-205
Gallium nitride (GaN) nanoflowers were synthesized on a silicon (Si) substrate at growth temperatures of 650 and 600 °C and under HCl:NH3 flow ratios of 1:20, 1:30, and 1:40 by hydride vapor phase epitaxy. Numerous nanorod and nanoneedle burs were formed within each nanoflower. The nanoflower size increased with increasing NH3 gas flow rate. The nanoflower formation mechanism is proposed based on cross-sectional scanning electron microscopy images and bright field image of scanning transmission electron microscopy. Nanoflowers were evolved from irregular regions with AlN–SiO2 grains on a Si substrate, i.e., the roughness of substrate affects nanoflower formation by causing nanoburs to protrude, exposing them to higher gas concentrations. 相似文献
13.
T. Sekiguchi H. Yamane M. Aoki T. Aoki M. Shimada 《Science and Technology of Advanced Materials》2013,14(2):91-94
Luminescence properties of hexagonal (h-) and cubic (c-) GaN freestanding single crystals were studied by means of cathodoluminescence spectroscopy. The h-GaN crystals of about 0.2–2 mm in dimension were synthesized at 750 °C by the reaction of Ga and N2 in a Na flux, while c-GaN crystals of about 0.3 mm or less in a K flux. The h-GaN showed rather strong band edge emission at room temperature compared with the crystal grown by using NaN3 as a nitrogen source. At 20 K, the band edge emission of h-GaN was split into four peaks. The main energy peak position was 3.478 eV, which was assigned as the A-free exciton emission. The energy position of the main peak of c-GaN was 3.268 eV. Assuming the binding energies of excitons in h- and c-GaN as 25 and 26 meV, respectively, the energy difference of bandgap between h-and c-GaN is estimated to be 209 meV. Since these crystals are free from strain from the substrates, the peak energies are reliable for the intrinsic GaN crystals. The full widths at half maximum of the emission of c-GaN were much broader than those of h-GaN, suggesting that the cubic phase is much defective compared with the hexagonal one. 相似文献
14.
15.
研究了以金属有机物化学气相沉积方法生长在6H-SiC衬底上的GaN光导型紫外探测器的光电流性质。通过光电流谱的测量,获得了GaN探测器在波长250nm-360nm范围近于平坦的光电流响应,并且观察到在365nm( ̄3.4eV)带边附近陡峭的截止边。测得GaN探测器在5V偏压下在360nm波长处的光电流响应度为133A/W,并得到了其响应度与外加偏压的关系。通过拟合光电信号强度与入射光调制频率的实验 相似文献
16.
按Strategies Unlimited最近的研究报告“GaN器件衬底:性能和市场评析”,对蓝紫光激光二极管、紫外LED和大功率射频(RF)器件的需求不断增加将为先进衬底,如GaN和AIN开辟很好的市场。采用GaN或AIN衬底可制备出高性能器件,因为这些衬底与器件有良好的晶格匹配和热匹配。随着市场需求扩大,许多公司正计划研制这些衬底;住友电工、Cree.三星Corning等大公司以及一些较小的公司,如CrystaIIS、The FOX Group,Kyma;Lumilog、TDI和TopGaN等;它们除努力研制这些先进衬底外,还致力于提高目前常用衬底(直径3″和更大的蓝宝石和SiC)的质量。全球涉足这方面工作的有48家公司和118所大学及研究中心。基于对这些器件的需求预测,全球对衬底的需求预测从21006年的3.4美元增长到2010年的8.8亿美元,2010年CraN和AIN衬底的销售额将超过50%。 相似文献
17.
18.
19.
依据文献中的气相反应路径,特别是寄生反应模型和刻蚀反应模型,指出对于存在冷壁面的水平式,加合物的反应路径对沉积起重要作用。在加合物路径中,对薄膜生长起决定作用的是TMGa和TMGa∶NH3,而环状化合物[(CH3)2Ga∶NH2]3形成的可能性很小,可以忽略。对于垂直式反应器,所有的反应物粒子均经过高温边界层区域,遵循热解路径。在高温条件下,对薄膜生长起决定作用的是MMG。纳米粒子的形成需要高温条件,并且纳米粒子的生长遵循CVD机理,可认为气相纳米粒子的主要成分可能是GaN。在高温条件下H2对GaN的刻蚀作用不可忽视。 相似文献