热原子层沉积钛掺杂氧化镓薄膜的光学性能

在250℃的低温下，以三甲基镓、四(二甲氨基)钛为前躯体源，O₃为反应气体，采用热原子层沉积制备了Ti掺杂Ga₂O₃(TGO)薄膜。Ga₂O₃和TiO₂的生长速率分别为0.037 nm/cycle和0.08 nm/cycle,TGO薄膜厚度低于理论计算值。X射线光电子能谱仪测试结果表明膜中Ti浓度随Ga₂O₃/TiO₂循环比减少而增加，O 1s、Ga 2p和Ti 2p的峰位置向较低的结合能移动，这是因为Ti原子取代了Ga原子的某些位点引起了结合能降低，表明Ti元素成功掺杂到Ga₂O₃薄膜中。TiO₂和Ga₂O₃的芯能级光谱分析表明薄膜中存有Ti⁴⁺和Ga³⁺离子。TGO薄膜的O 1s芯能级光谱中Ga-O键随着Ti-O键含量增加而下降，表明T...     

蓝宝石衬底上生长的Ga2+xO3-x薄膜的结构分析

利用卢瑟夫背散射/沟道技术和金属有机化学气相沉积方法, 对蓝宝石衬底上 在不同温度、压强下生长的Ga_2+xO_3-x薄膜进行结构和结晶品质的测量与分析; 并结合高分辨X射线衍射分析技术, 通过对其对称(402)面的θ–2θ及ω扫描, 确定了其结构类型及结晶品质. 实验表明: 在相同的生长温度(500 ℃)下, 结晶品质随压强的下降而变好, 生长压强为15 Torr (1 Torr=133.322 Pa)的样品其结晶品质最好, 沿轴入射之比χ_min值为14.5%; 在相同的生长压强(15 Torr)下, 结晶品质受生长温度的影响不大, 所以, 生长温度不是改变结晶品质的主要因素; 此外, 在相同的生长条件下制备的样品, 分别经过700, 800和900 ℃退火后, 其结晶品质随退火温度的变化而变化. 退火温度为800 ℃的样品的结晶品质最好, χ_min值为11.1%; 当退火温度达到900 ℃时, 样品部分分解; 经热处理的样品其X射线衍射谱中有一个强的Ga₂O₃ (402)面衍射峰, 其半峰全宽为0.5°, 表明该Ga₂O₃外延膜是(402)择优取向. 关键词： 氧化镓 卢瑟夫背散射 X射线衍射 结晶品质     

X射线吸收谱对Ga0.946Mn0.054As薄膜中缺陷的研究

采用低温分子束外延法(LT-MBE)制备出Ga_0.946Mn_0.054As稀磁半导体(DMS)薄膜.通过X射线吸收谱(XAS)研究影响Ga_0.946Mn_0.054As薄膜性质的主要缺陷Mn间隙原子(Mn_I)和As反位原子(As_Ga).实验结果表明,在较低生长温度(T_S=200℃)下Ga_0.946Mn_{0.054 关键词： 0.946}Mn_0.054As稀磁半导体')" href="#">Ga_0.946Mn_0.054As稀磁半导体 X射线吸收谱 As反位缺陷 Mn间隙原子     

Ga2O3组分对Tm3+掺杂GeO2-Ga2O3-Li2O-BaO-La2O3玻璃的光谱性能影响

制备了Tm³⁺(8.0mol%)掺杂(77-x)GeO₂-xGa₂O₃-8Li₂O-10BaO-5La₂O₃(x=4,8,12,16)系列玻璃.系统地研究了Ga₂O₃从4mol%变化到16mol%时，玻璃的光谱性质与热学性质的变化规律.差热分析表明，随着Ga₂O₃含量的增加，锗酸盐玻璃的热稳定性增加.运用Judd-Ofelt(J_O)理论计算得到了Tm³⁺在不同Ga₂O₃含量的GeO₂-Ga₂O₃-Li₂O-BaO-La₂O₃玻璃中的J-O强度参数(Ω₂，Ω₄，Ω₆)及Tm³⁺各激发能级的自发跃迁概率、荧光分支比以及辐射寿命等光谱参量.在808nm激光二极管的激发下，测试并分析了Ga₂O₃对Tm³⁺荧光光谱特性的影响.随着Ga₂O₃从4mol%增加到16mol%，Tm³⁺在1.8μm处的荧光强度呈现先减弱后增强的特性.当Ga₂O₃含量大约在12mol%时，Tm³⁺在1.8μm处的荧光强度最弱，受激发射截面达到最小.还初步讨论了Ga₂O₃对玻璃结构与光谱参数的影响规律. 关键词： 3+掺杂锗酸盐玻璃')" href="#">Tm³⁺掺杂锗酸盐玻璃 光谱性能 Judd-Ofelt参数 热稳定性     

TiN/Al2O3纳米多层膜的共格外延生长及超硬效应

采用多靶磁控溅射法制备了一系列具有不同Al₂O₃调制层厚度的TiN/Al₂O₃纳米多层膜. 利用X射线能量色散谱、X射线衍射、扫描电子显微镜、高分辨透射电子显微镜和微力学探针表征了多层膜的成分、微结构和力学性能. 研究结果表明，在TiN/Al₂O₃纳米多层膜中，单层膜时以非晶态存在的Al₂O₃层在厚度小于1.5 nm时因TiN晶体层的模板效应而晶化，并与TiN层形成共格外延生长，相应地，多层膜产生硬度明显升高的超硬效应，最高硬度可达37.9 GPa. 进一步增加多层膜中Al₂O₃调制层的层厚度，Al₂O₃层逐渐形成非晶结构并破坏了多层膜的共格外延生长，使得多层膜的硬度逐步降低. 关键词： 2O₃纳米多层膜')" href="#">TiN/Al₂O₃纳米多层膜 外延生长 非晶晶化 超硬效应     

MoO3在多孔γ-Al2 O3中固熔分散的研究

用MoO₃与多孔γ-Al₂O₃载体以机械混合法制备了一系列MoO₃/γ-Al₂O₃样品.用扫描电子显微镜、X射线衍射、X射线光电子能谱分析、综合热分析(TG/DTA)和正电子湮没谱学研究了MoO₃加载于γ-Al₂O₃后固熔分散过程.分别测量了不同含量的MoO₃/γ-Al_{2关键词： 正电子湮没谱学 三氧化钼 分散 逐次加载}     

P2S5/NH4OH处理GaAs(100)表面的电子能谱研究

采用俄歇电子能谱(AES)和X射线光电子能谱(XPS)研究了P₂S₅/NH₄OH钝化液处理的GaAs(100)表面的微观特性。AES测量表明,在钝化膜和GaAs衬底之间的界面处无O组分,只有P和S组分。XPS测量分析指出,经过P₂S₅/NH₄OH溶液处理后,GaAs表面处Ga₂O₃和As₂O_{3关键词：}     

Ti和蓝宝石的界面反应

在超高真空中用电子束蒸发在抛光的(1102)取向的蓝宝石(α-Al₂O₃)衬底上蒸镀500nm的Ti膜,在恒温炉中退火,然后用XRD(包括一般的和小角度的X射线衍射),AES(俄歇电子谱,包括深度剖面分布和通过界面的谱形分析)和SIMS(二次离子质谱)等表面分析技术详细研究了从室温至850℃,Ti与α-Al₂O₃的固相界面反应.结果表明室温及300℃,30min退火已有反应,Al₂O_{3< 关键词：}     

基于HfO2插层的Ga2O3基金属-绝缘体-半导体结构日盲紫外光电探测器

作为一种新兴的超宽带隙半导体, Ga₂O₃在开发高性能的日盲紫外光电探测器方面具有独特的优势.金属-半导体-金属结构因其制备方法简单、集光面积大等优点在Ga₂O₃日盲紫外光电探测器中得到了广泛的应用.本文在传统的金属-半导体-金属结构Ga₂O₃日盲紫外光电探测器的基础上,利用原子层沉积技术引入高介电性和绝缘性的氧化铪(HfO₂)作为绝缘层和钝化层,制备出带有HfO₂插层的金属-绝缘体-半导体结构的Ga₂O₃日盲紫外光电探测器,显著降低了暗电流,提升了光暗电流比,同时提高了器件的比探测率和响应速度,为未来Ga₂O₃在高性能弱光探测器件制备提供了一种新通用策略.     

YBa2Cu3O7-x涂层导体的外延生长和性能对CeO2缓冲层的依赖性

利用倾斜衬底沉积法在无织构的金属衬底上生长了MgO双轴织构的模板层，在这一模板层上实现了YBa₂Cu₃O_7-x薄膜的外延生长.在外延YBa₂Cu₃O_7-x薄膜前，依次沉积了钇稳定的立方氧化锆和CeO₂作为缓冲层.利用X射线衍射2θ扫描、扫描、Ω扫描和极图分析测定了这些膜的结构和双轴织 关键词： 2Cu₃O_7-x镀膜导体')" href="#">YBa₂Cu₃O_7-x镀膜导体 2缓冲层')" href="#">CeO₂缓冲层 厚度依赖性 外延生长     

Annealing effects on the properties of Ga2O3 thin films grown on sapphire by the metal organic chemical vapor deposition

We have prepared the gallium oxide (Ga₂O₃) thin films on sapphire substrates by the metal organic chemical vapor deposition (MOCVD) technique. We have compared the two films with and without the thermal annealing by using the X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and the photoluminescence (PL) spectra. Postdeposition annealing of amorphous Ga₂O₃ films was found to increase the degree of crystallization and the surface roughness. The PL emission intensities of bands in the blue–green and the ultraviolet regions increased by the thermal annealing.     

Formation of high quality gallium nitride thin films on Ga-diffused Si(1 1 1) substrate

High quality gallium nitride thin films have been successfully grown on the Ga-diffused Si(1 1 1) substrates through ammoniating Ga₂O₃ thin films deposited by r.f. magnetron sputtering. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscope (AFM) and photoluminescence (PL) were used to characterize the synthesized samples. The analyses reveal that the formed films are high quality polycrystalline hexagonal gallium nitride. The as-formed GaN films show a flat surface topography with RMS roughness varied from 29 to 48 Å. The strong near-band-edge-emission peak around 368 nm was observed at room temperature. This is a novel method to fabricate GaN thin films based on the direct reaction between Ga₂O₃ and NH₃ on the Ga-diffused Si(1 1 1) substrates.     

Enhanced luminescence from transparent Ni-doped MgO–Al2O3–SiO2 glass ceramics by Ga2O3 addition

Transparent Ni²⁺-doped MgO–Al₂O₃–SiO₂ glass ceramics without and with Ga₂O₃ were synthetized. The precipitation of spinel nanocrystals, which was identified as solid solutions in the glass ceramics, could be favored by Ga₂O₃ addition and their sizes were about 7.6 nm in diameter. The luminescent intensity of the Ni²⁺-doped glass ceramics was largely enhanced by Ga₂O₃ addition which could mainly be caused by increasing of Ni²⁺ in the octahedral sites and the reduction of the mean frequency of phonon density of states in the spinel nanocrystals of solid solutions. The full width at half maximum (FWHM) of emissions for the glass ceramics with different Ga₂O₃ content was all more than 200 nm. The emission lifetime increased with the Ga₂O₃ content and the longest lifetime is about 250 μs. The Ni²⁺-doped transparent glass ceramics with Ga₂O₃ addition have potential application as broadband optical amplifier and laser materials.     

氧化镓薄膜的制备及其日盲紫外探测性能研究

采用射频磁控溅射方法在蓝宝石单晶衬底上沉积氧化镓(Ga2O3)薄膜,并通过光刻剥离工艺(Lift-off)制备了金属-半导体-金属结构的Ga2O3日盲紫外探测器。对不同温度下沉积的Ga2O3薄膜分析表明,在800℃下获得的薄膜结晶质量最好,薄膜的导电性则随着沉积温度的上升先增大后减小。在800℃制备的β-Ga2O3薄膜的可见光透光率大于90%,光学吸收边在255 nm附近。在10 V偏压下,探测器的暗电流约为1n A,光电流达800 n A,对紫外光响应迅速。器件的响应度达到0.3 A/W,260 nm波长处的响应度是290 nm波长对应响应度的40倍,可实现日盲紫外波段的探测。     

High-responsivity solar-blind photodetector based on MOCVD-grown Si-doped β-Ga_2O_3 thin film

Si-doped β-Ga_2O_3 films are fabricated through metal-organic chemical vapor deposition(MOCVD). Solar-blind ultraviolet(UV) photodetector(PD) based on the films is fabricated by standard photolithography, and the photodetection properties are investigated. The results show that the photocurrent increases to 11.2 m A under 200 μW·cm-2254 nm illumination and ±20 V bias, leading to photo-responsivity as high as 788 A·W~(-1). The Si-doped β-Ga_2O_3-based PD is promised to perform solar-blind photodetection with high performance.     

基于GaN同质衬底的高迁移率AlGaN/GaNHEMT材料

研究了表面预处理对GaN同质外延的影响,获得了高电子迁移率AlGaN/GaN异质结材料.通过NH_3/H_2混合气体与H_2交替通入反应室的方法对GaN模板和GaN半绝缘衬底进行高温预处理.研究结果表明,NH_3/H_2能够抑制GaN的分解,避免粗糙表面,但不利于去除表面的杂质,黄光带峰相对强度较高;H_2促进GaN分解,随时间延长GaN分解加剧,导致模板表面粗糙不平,AlGaN/GaN HEMT材料二维电子气迁移率降低.采用NH_3/H_2混合气体与H_2交替气氛模式处理模板或衬底表面,能够清洁表面,去除表面杂质,获得平滑的生长表面和外延材料表面,有利于提高AlGaN/GaN HEMT材料电学性能.在GaN衬底上外延AlGaN/GaN HEMT材料,2DEG迁移率达到2113 cm~2/V·s,电学性能良好.     

超宽禁带半导体β-Ga_2O_3及深紫外透明电极、日盲探测器的研究进展

β-Ga_2O_3是一种新型的超宽禁带氧化物半导体,禁带宽度约为4.9 eV,对应日盲区,对波长大于253 nm的深紫外一可见光具有高的透过率,是天然的日盲紫外探测及深紫外透明电极材料.本文介绍了Ga_20_3材料的晶体结构、基本物性与器件应用,并综述了β-Ga_2O_3在深紫外透明导电电极和日盲紫外探测器中的最新研究进展.Sn掺杂的Ga_2O_3薄膜电导率可达到32.3 S/cm,透过率大于88%,但离商业化的透明导电电极还存在较大差距.在日盲紫外探测器应用方面,基于异质结结构的器件展现出更高的光响应度和更快的响应速度,ZnO/Ga_2O_3核/壳微米线的探测器综合性能最佳,在-6 V偏压下其对254 nm深紫外光的光响应度达1.3×10~3A/W,响应时间为20μs.     

等离子增强原子层沉积低温生长GaN薄膜

采用等离子增强原子层沉积技术在低温下于单晶硅衬底上成功生长了Ga N多晶薄膜,利用椭圆偏振仪、低角度掠入射X射线衍射仪、X射线光电子能谱仪对薄膜样品的生长速率、晶体结构及薄膜成分进行了表征和分析.结果表明,等离子增强原子层沉积技术生长Ga N的温度窗口为210—270?C,薄膜在较高生长温度下呈多晶态,在较低温度下呈非晶态;薄膜中N元素与大部分Ga元素结合成N—Ga键生成Ga N,有少量的Ga元素以Ga—O键存在,多晶Ga N薄膜含有少量非晶态Ga_2O_3.     

Ga掺入对立方相MgZnO薄膜晶体结构的影响

采用金属有机物化学气相沉积方法生长了立方相Mg_0.56Zn_0.44O：Ga薄膜,Ga在MgZnO中的摩尔分数为2.8%~4.5%。低掺杂水平的MgZnO可以保持其良好的结晶特性。随着Ga元素的摩尔分数升高至3.1%、3.3%与4.5%,立方相MgZnO中分别出现了Ga₂O₃、ZnO与ZnGa₂O₄分相。其中,Ga₂O₃与ZnGa₂O₄相的出现是由于Ga的掺杂使这两相在MgZnO基质中饱和析出,而ZnO分相被归因于Ga的引入部分破坏了立方MgZnO的亚稳态结构状态,使组分原本就处于分相区的立方MgZnO出现相分离。     

Characterization of hetero-interfaces between group III nitrides formed by PLD and various substrates

We have grown group III nitride epitaxial films on various substrates by pulsed laser deposition and investigated structural properties of the surfaces and the hetero-interfaces using grazing incidence angle X-ray reflectivity (GIXR) and atomic force microscopy (AFM). It has been found that hetero-interfaces between PLD AlN and conventional substrates such as Al₂O₃ and Si are quite abrupt (about 0.5 nm) probably due to a less reactive growth ambience. However, we observed a thin interfacial layer (less than 10 nm) at the hetero-interface between AlN and (Mn,Zn)Fe₂O₄. The surface roughness of AlN is mainly determined by the extent of the lattice mismatch. It has been also found that the roughness at the hetero-interface between GaN and AlN formed by PLD coincides with the surface roughness of the AlN layer.