38 resultados para GSMBE


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于2010-11-23批量导入

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在国内首次用NH_3作氮源的GSMBE方法在α-Al_2O_3衬底上生长出了GaN单晶外延膜。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,室温阴极发光谱上只有一个强而锐的近带边发光峰,谱峰位于372nm处,谱峰半高宽为14nm(125meV)。

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于2010-11-23批量导入

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于2010-11-23批量导入

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国家九五计划,中国博士后基金

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用MOCVD在(100)、GSMBE在(100)和(111)B GaAs上生长了GaInP外延层.PL测试表明,(100)衬底上GaIn PL 峰的能量比计算的带隙分别小43(GSMBE生长)和104meV(M(CVD生长).用Kurtz等人的模型对MOCVD和GSMBE生长的GaInP中有序度的不同进行了解释.并讨论了衬底晶向对GaInP中有序程度的影响.

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在国产第一台CEB(Chemical beam epitaxy)设备上,用GSMBE(Gas source molecular beam epitaxy)技术在国内首次研究了InGaAs/InP匹配和应变多量子阱超晶格材料的生长,用不对称切换方法成功地生长了高质量的匹配和正负应变超晶格材料,并用双晶X-射线衍射技术对样品进行了测试和分析。结果表明,我们在国产地一台CBE设备上用GSMBE技术采用非对称切换方法生长的超晶格材料质量很好。

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报道通过在位组分调整,配合X射线双晶衍射测试和光致发光测试,生长了与InP精确匹配的GaLnAsP(失配度达4×10~(-4)).生长了GaInAs/InP量子阱结构的光致发光半峰宽达5.72meV.实验表明源炉档板开启 后生长速率是不均匀的,这对生长量子阱和DBR结构是个值得注意的问题,经考虑生长速率变化后生长的面发射激光器结构样片的反射率谱与理论计算的结果很好地相符.

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Hexagonal GaN is grown on a Si(111) substrate with AlN as a buffer layer by gas source molecular beam epitaxy (GSMBE) with ammonia. The thickness of AlN buffer is changed from 9 to 72 nm. When the thickness of AlN buffer is 36 nm, the surface morphology and crystal quality of GaN is optimal. The in-situ reflection high energy electron diffraction (RHEED) reveals that the transition to a two-dimensional growth mode of AlN is the key to the quality of GaN. However, the thickness of AlN buffer is not so critical to the residual in-plane tensile stress in GaN grown on Si(111) by GSMBE for AlN thickness between 9 to 72 nm.

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We describe the growth of GaN on Si(111) substrates with AlxGa1-xN/AlN buffer layer by ammonia gas source molecular beam epitaxy (NH3-GSMBE). The influence of the AlN and AlxGa1-xN buffer layer thickness and the Al composition on the crack density of GaN has been investigated. It is found that the optimum thickness is 120 and 250 nm for AlN and AlxGa1-xN layers, respectively. The optimum Al composition is between 0.3 < x < 0.6. (c) 2005 Elsevier B.V. All rights reserved.

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Three n-p-n Si/SiGe/Si heterostructures with different layer thickness and doping concentration have been grown by a home-made gas source molecular-beam epitaxy (GSMBE) system using phosphine (PH3) and diborane (B2H6) as n-and p-type in situ doping sources, respectively. Heterojunction bipolar transistors (HBTs) have been fabricated using these structures and a current gain of 40 at 300 K and 62 at 77 K have been obtained. The influence of thickness and doping concentration of the deposited layers on the current gain of the HBTs is discussed. (C) 2000 Elsevier Science B.V. All rights reserved.

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As reported by other authors, we have also observed that the Si growth rate decreases with increasing phosphine (PH3) flow rate in gas source-Si molecular beam epitaxy using phosphorous (P) as a n-type dopant. Why small quantity PH3 can affect Si growth rate? Up to now, the quantitative characterization of PH3 flow influence on Si growth rate is little known. In this letter, the PH, influence will be analyzed in detail and a model considering strong P surface segregation and its absorption of hydrogen will be proposed to characterize the effect. (C) 2000 Elsevier Science B.V. All rights reserved.

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In situ doping for growth of n-p-n Si/SiGe/Si heterojuction bipolar transistor (HBT) structural materials in Si gas source molecular beam epitaxy is investigated. We studied high n-type doping kinetics in Si growth using disilane and phosphine, and p-type doping in SiGe growth using disilane, soild-Ge, and diborane with an emphasis on the effect of Ge on B incorporation. Based on these results, in situ growth of n-p-n Si/SiGe/Si HBT device structure is demonstrated with designed structural and carrier profiles, as verified from characterizations by X-ray diffraction, and spreading resistance profiling analysis. (C) 2000 Elsevier Science B.V. All rights reserved.

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We have found that GaN epilayers grown by NH3-source molecular beam epitaxy (MBE) contain hydrogen. Dependent on the hydrogen concentration, GaN on (0001) sapphire can be either under biaxially compressive strain or under biaxially tensile strain. Furthermore, we notice that background electrons in GaN increase with hydrogen incorporation. X-ray photoelectron spectroscopy (XPS) measurements of the N1s region indicate that hydrogen is bound to nitrogen. So, the microdefect Ga...H-N is an effective nitrogen vacancy in GaN, and it may be a donor partly answering for the background electrons. (C) 1999 Elsevier Science B.V. All rights reserved.