不同衬底上低温生长的ZnO晶体薄膜的结构及光学性质比较

采用电子束反应蒸发方法,在单晶Si(001)及玻璃衬底上低温外延生长了沿c轴高度取向的单晶ZnO薄膜,并对沉积的ZnO晶体薄膜的结构和光学性质进行了分析比较。通过对ZnO薄膜的X射线衍射(XRD)分析及光致荧光激发谱(PLE)测量,研究了衬底材料结构特性、生长温度及反应气氛中充O     

不同衬底上低温生长的ZnO晶体薄膜的结构及光学性质比较

采用电子束反应蒸发方法,在单晶Si（001）及玻璃衬底上低温外延生长了沿C轴高度取向的单晶ZnO薄膜,并对沉积的ZnO晶体薄膜的结构和光学性质进行了分析比较。通过对ZnO蒲膜的X射线衍射（XRD）分析及光致荧光激发谱（PLE）测量,研究了衬底材料结构特性、生长温度及反应气氛中充O2对ZnO薄膜的晶体结构和晶体光学吸收特性的影响。结果表明：①衬底温度对沉积的ZnO薄膜的晶体结构影响显,玻璃衬底上生长ZnO薄膜的最佳温度比Si(001)衬底上生长的最佳温度要高70℃;②虽在最佳生长条件下获得的ZnO薄膜的的XRD结果（半高宽和衍射强度）相近,但光学吸收特性有较大差异,Si(001)衬底上生长的ZnO薄膜优于玻璃衬底上生长的ZnO薄膜;③反应气氛中的O2分压对XRD结构影响不大,但对PLE谱影响显,充O2后能明显改善吸收边特性。     

Si(111)衬底上生长的立方MgxZn1-xO晶体薄膜

在国际上第一次采用电子束反应蒸发法在Si(111)衬底上生长了MgxZn1-xO晶体薄膜.能量色散X射线(EDX)特征能谱及X射线衍射(XRD)分析表明薄膜呈立方结构,薄膜的晶面取向依赖于生长温度,在200C温度下生长得到高度(200)取向的立方MgxZn1-xO薄膜,温度过高时得到多晶薄膜.对高度(200)取向的立方MgxZn1-xO薄膜的光荧光激发谱(PLE)分析表明其光学带隙为4.20eV,相对于MgO的带隙红移量为3.50eV.XRD分析还表明立方MgxZn1-xO薄膜与MgO衬底之间的晶格失配仅为0.16%.这使得高质量立方MgxZn1-xO/MgO多量子阱材料的制备成为可能.     

低温生长Zn1-xCoxO(x=0.33)薄膜的微结构和磁性

用电子束反应蒸镀法在低温生长了Zn1-xCoxO薄膜.Co含量x高达0.33的Zn1-xCoxO薄膜仍具有类ZnO的纤锌矿结构,没有杂质相,Co的化合价为 2.场冷和零场冷M-T及M-H曲线表明,Zn1-xCoxO(x=0.33)薄膜在低温下具有铁磁性;随着温度的升高,其剩磁和矫顽力均逐渐下降,在65 K以上趋于零,显示出超顺磁性.Zn1xCoxO薄膜的低温铁磁性起源于Co2 离子之间的双交换相互作用及载流子诱导的sP d交换耦合作用,而从低温(＜65 K)铁磁态到高温(＞65 K)超顺磁态的转变可归因于薄膜的纳米晶小尺寸效应.     

Si(111)衬底上生长的立方MgxZn1-x晶体薄膜

在国际上第一次采用电子束反应蒸发法在Si(111)衬底上生长了MgxZn1-xO晶体薄膜。能量色散X射线(EDX)特征能谱及X射线衍射(XRD)分析表明薄膜呈立方结构，薄膜的晶面取向依赖于生长温度，在200℃温度下生长得到高度(200)取向的立方MgxZn1-xO薄膜，温度过高时得到多晶薄膜。对高度(200)取向的立方MgxZn1-xO薄膜的光荧光激发谱(PLE)分析表明其光学带隙为4．20eV，相对于MgO的带隙红移量为3．50eV。XRD分析还表明立方MgxZn1-xO薄膜与MgO衬底之间的晶格失配仅为0．16％。这使得高质量立方MgxZn1-xO多量子阱材料的制备成为可能。     

立方相MgxZn1-xO纳米晶体薄膜的物理特性

介绍了在Si衬底和石英玻璃衬底上生长的立方相MgxZn1-xO(0.55≤x≤1)晶体薄膜的物理特性,AFM和XRD等微结构特性表征显示了良好的表面形貌和高度的(111)取向生长特性.采用Manifacier方法,根据透射光谱中的干涉峰,计算得到立方相MgxZn1-xO薄膜的折射率.与已报道的六方相MgxZn1-xO(0≤x≤0.5)薄膜的折射率相类似,在400～800nm的可见光区域,不同Mg含量的立方相MgxZn1-xO薄膜,其折射率随入射波长的色散关系遵循一阶Sellmeier方程.对给定400nm的入射光波长,当薄膜中的Mg含量由55%增至100%时,其折射率由1.89衰减至1.73.     

Zn掺杂SnS薄膜的表征及光学特性

真空共蒸发制备掺Zn(2%,4%(质量比))的SnS薄膜。研究热处理对Zn掺杂SnS薄膜的结构、表面形貌、化学组分及光学特性的影响。实验给出2%掺Zn薄膜经300℃,40 min热处理后,得到正交晶系的SnS多晶薄膜。掺Zn可一定程度抑制薄膜中S的损失,使薄膜体内Sn∶S元素化学计量得到改善,从未掺Zn的Sn∶S比为1.90∶1降到1.38∶1(2%)及1.36∶1(4%)。掺Zn后SnS薄膜的吸收边都发生红移,光吸收系数高达105cm-1。未掺Zn薄膜的直接光学带隙1.95 eV,掺Zn是1.375 eV(2%)和1.379 eV(4%)。Sn和S在薄膜中分别呈+2和-2价态,Zn以间隙和替位两种状态存在。     

衬底温度对电子束反应蒸发生长的ZnxCo1-xO薄膜性能的影响

采用电子束反应蒸发法生长ZnxCo1-xO薄膜。通过X射线衍射、场发射扫描电子显微镜、光致荧光光谱（PL）、室温M-H曲线等测量研究衬底温度对Zn0∞C00-250薄膜微结构及光学、磁学特性的影响。结果表明，250～350℃温度范围内生长的Zn0.75Co0.25O薄膜具有单一的纤锌矿结构，但当温度超过400℃时产生CoO杂相偏析。在300或350℃衬底温度下生长Zn0.75Co0.25O薄膜具有室温铁磁性，PL测量结果表明Zn0.75Co0.25O薄膜的室温铁磁性很可能起源于氧空位缺陷诱导的自旋劈裂杂质带机制．而250℃生长Zn0.75Co0.25O薄膜在室温下呈现超顺磁性，超顺磁性的产生是Zn0.75Co0.25O晶粒的小尺寸效应所导致。     

退火对立方相 MgxZn1-xO薄膜的结构和光学性质影响

在蓝宝石（0001）衬底上低温生长立方相MgxZn1-xO（x〉0．5）晶体薄膜，用X射线衍射（XRD）和透射光谱分析高温退火对薄膜的结构和光学性质的影响．结果表明;对Mg0．53Zn0．47O薄膜，在900℃的退火温度下，（0002）衍射峰以及透射光谱上双吸收边的出现均表明有六方结构从其立方结构中分离出来；但对于Mg含量高于55％的样品，即使经历了1000℃的高温退火，也不会有任何相分裂现象出现．而电学测试结果表明，高温下热稳定性良好的立方相Mg0．55Zn0．45O晶体薄膜还能用于金属-绝缘体-半导体的绝缘层，并且漏电流小．由此可以判断，x≥0．55的超饱和MgZn1-xO薄膜具有稳定的立方相晶体结构和优良的光学、电学性质，因而是制作高质量的光电子器件和量子阱激光器的理想材料．     

石英衬底上的BPxN1-x薄膜沉积及P对其光学带隙调制的研究

以光学石英为衬底,采用热丝辅助射频等离子体增强化学气相沉积方法(HF-PECVD)沉积了BPxN1-X薄膜.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱(EDAX)、紫外-可见(UV-VIS)等测试手段研究了薄膜的化学组成、结晶状况,以及P元素掺杂对BPxN1-X薄膜材料光学带隙的调制规律.结果表明,所沉积薄膜具有多晶团聚、定向生长的特点,其表面形貌随时间而变化,最后发展成多晶球状密堆成膜,与石英衬底结合牢固.BPxN1-x薄膜的磷元素相对含量随磷烷流量增加而增加,光学带隙相应窄化.通过控制磷的掺杂量可以有效调整该薄膜材料的光学带隙.     

Optical properties of porous anodic aluminum oxide thin films on quartz substrates

Porous anodic aluminum oxide (AAO) thin films on quartz substrates were fabricated via evaporation of a 100-nm thick Al, followed by anodization with different durations and pore widening and Al removal by chemical etching. The transmittance and reflectance of AAO films on quartz substrates were measured by optical spectrophotometry. The microstructure and morphology were examined by scanning electron microscopy. The pore diameter of AAO films after pore widening and Al removal is 60 ± 4 nm and the interpore distance is 88 ± 5 nm. It is found that the reflectance decreases and the transmittance increases with the increase of the anodization time and pore widening. Compared to a bare substrate, the transmittance of AAO films after pore widening and Al removal is about 3.0% higher, while the reflectance is about 3.0% lower over a wide wavelength range. Additionally, after pore widening and Al removal, when AAO films are prepared on both sides of the quartz substrate, the highest transmittance is about 99.0% in the wavelength range 570-680 nm. The optical constants and thickness of AAO films after pore widening and Al removal were retrieved from normal incidence transmittance data. Results show that the refractive index is lower than 1.25 in the visible optical region and that the porosity is about 0.70.     

Effect of annealing on the structural and optical properties of InSe bilayer thin films

InSe bilayer thin films with different thickness were prepared on to a glass substrate by sequential thermal evaporation. Preparation and post deposition treatment conditions were optimized in order to achieve effective bilayer mixing. The influence of bilayer film thickness and annealing temperature on the structural and optical properties was investigated. The prepared films were characterized by X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray analysis, UV-Visible spectroscopy, photoconduction and resistivity measurement. Structural studies show that the material undergoes phase transition with thickness, due to co-existence of many phases. Morphological analysis revealed that Se content plays an important role in determining the surface morphology of the film. It has been observed that grain growth and grain splitting phenomena depend on film thickness and annealing temperature. From the photoconduction measurements, the photocurrent increases rapidly when the sample is illuminated using 135 K Lux of white light. Absorption coefficient is in the order of 10⁴ cm⁻¹, makes the InSe thin film useful for the preparation of absorber layer in hybrid solar cell.     

Correlation study between structural, magnetic and transport properties of annealed Co thin films

This paper presents structural, magnetization and transport properties measurements carried out on as-deposited Co (400 Å) thin film as well as samples annealed in the temperature range 100-500 °C in steps of 100 °C for 1 h. The samples used in this work were deposited on float glass substrates using ion beam sputtering technique. The magnetization measurements carried out using MOKE technique, clearly indicates that as-deposited as well as annealed samples up to 500 °C show well saturation magnetization with applied magnetic field. The as-deposited sample shows coercivity value (H_c) of 26 Oe, and it is increased to 94 Oe for 500 °C-annealed sample. A minimum coercivity value of 15 Oe is obtained for 200 °C annealed sample. The XRD measurements of as deposited films show microcrystalline nature of Co film, which becomes crystalline with increase in annealing temperature. The corresponding resistivity measurements show gradual decrease in resistivity. AFM technique was employed to study the surface morphology of as deposited film as well as annealed thin films. Observed magnetization, and resistivity behaviour is mainly attributed to the (i) change in crystal structure (ii) increase in grain size and (iii) stress relaxation due to the annealing treatment.     

Structural and optical properties of electron beam evaporated CdSe thin films

Thin films of cadmium selenide (CdSe) as a semiconductor is well suited for opto-electronic applications such as photo detection or solar energy conversion, due to its optical and electrical properties, as well as its good chemical and mechanical stability. In order to explore the possibility of using this in optoelectronics, a preliminary and thorough study of optical and structural properties of the host material is an important step. Based on the above view, the structural and optical properties of CdSe films have been studied thoroughly in the present work. The host material, CdSe film, has been prepared by the physical vapour deposition method of electron beam evaporation (PVD: EBE) technique under a pressure of 5 × 10⁻⁵ mbar. The structural properties have been studied by XRD technique. The hexagonal structure with a preferred orientation along the (0 0 2) direction of films has been confirmed by the X-ray diffraction analysis. The films have been analysed for optical band gap and absorbed a direct intrinsic band gap of 1·92 eV.     

Structural and magnetic properties of FePd and CoPd alloy epitaxial thin films grown on MgO single-crystal substrates with different orientations

FePd and CoPd alloy thin films were prepared on MgO single-crystal substrates of (001)_B1, (110)_B1, and (111)_B1 orientations at 600 °C by ultra high vacuum rf magnetron sputtering. L1₀-FePd(001) films with the c-axis perpendicular to the substrate surface are obtained on MgO(001)_B1 substrates. FePd epitaxial films consisting of L1₀(110) and L1₀(011) crystals are formed on MgO(110)_B1 substrates. The c-axis of L1₀(110) crystal is parallel to the substrate surface, whereas that of L1₀(011) crystal is 44° canted from perpendicular direction. L1₀-FePd(111) films with the c-axis 54° canted from the perpendicular direction are formed on MgO(111)_B1 substrates. L1₀ ordering degree of these FePd films varies depending on the substrate orientation. On the other hand, disordered CoPd thin films of (001)_A1, (110)_A1, and (111)_A1 orientations epitaxially grow on MgO substrates of (001)_B1, (110)_B1, and (111)_B1 orientations, respectively. The magnetization properties of L1₀ ordered FePd and A1 disordered CoPd thin films are influenced by the crystal structure, the ordering degree, and the film orientation.     

Ti/TiO2多层膜的光电性能研究

用真空蒸发和自然氧化法在玻璃基底上制备了Ti／TiO2多层膜，并检测了薄膜的光电性能。电性能检测表明Ti／TiO2多层膜存在类负阻效应，多层膜的层间的类负阻效应比表面的更明显，薄膜的层间电阻率高于表面电阻率；用分光光度计测得试样退火前后的透射谱；用X射线衍射仪和扫描电镜检测了Ti／TiO2多层膜的晶体结构和表面形貌。     

Zn_(1-x)Mn_xS稀磁半导体的合成与光学性能

通过水热法制备不同掺杂浓度的Zn_(1-x)Mn_xS(x=0.00,0.02,0.05,0.07)稀磁半导体材料,研究Mn~(2+)掺杂浓度对ZnS纳米棒微观结构和光学性能的影响。采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED)、X射线能量色散分析谱仪(XEDS)和紫外可见吸收光谱(UV-vis)对样品的晶体结构、形貌和光学性能进行表征。结果表明:制备的所有样品均具有结晶良好的纤锌矿结构,没有杂峰出现,生成纯相Zn_(1-x)Mn_xS纳米晶。样品形貌为纳米棒状结构,分散性良好。掺杂的Mn元素进入到ZnS纳米晶中,Mn~(2+)替代了Zn~(2+),而且随着Mn掺杂量的增加晶格常数减小。同时UV-vis光谱发现样品的光学带隙增大,发生了蓝移现象。     

Ar气氛中退火对Zn0.66Co0.34O薄膜性能的影响

采用电子束反应蒸发生长Zn0.66Co0.34O薄膜,生长温度仅为250℃,尔后在Ar气氛中500℃退火1h.场发射扫描电镜测量显示薄膜由粒径约10～20nm的晶粒所构成.X射线衍射测量表明薄膜在退火前后均呈类ZnO的六方纤锌矿结构.振动样品磁场计测量室温下薄膜的M-H曲线,结果显示退火前薄膜呈超顺磁性,退火后则为铁磁、超顺磁混合态,这表明退火提供了足够能量使得薄膜中一部分磁性Zn0.66Co0.34O小晶粒融合成大晶粒,新晶粒的尺寸超过了Zn0.66Co0.34O材料的超顺磁临界半径而表现出铁磁性,但由于另有部分晶粒仍表现为超顺磁性,故薄膜呈铁磁性与超顺磁性的混合态.     

化学镀Co-P薄膜的磁性及研究

采用化学镀法制备了Co-P磁记录薄膜.当薄膜厚度为0.3μm时,矫顽力可达4.54×104A/m,剩余磁化强度为0.068T.X射线衍射分析表明,当Co-P薄膜较薄时,薄膜结构中无明显择优取向,晶粒较小,此时矫顽力较高;当厚度增加至3～4μm以上时,结构中择优取向明显,晶粒较大,此时薄膜的矫顽力较低.将其应用于磁旋转编码器的磁鼓记录介质,制成直径φ40mm的磁鼓,当原始充磁磁极对数为512时,脉冲计数完整,输出信号强,波形稳定.