Fabrication of Bismuth Telluride-Based Alloy Thin Film Thermoelectric Devices Grown by Metal Organic Chemical Vapor Deposition

Bismuth–antimony–telluride based thin film materials were grown by metal organic vapor phase deposition (MOCVD). A planar-type thermoelectric device was fabricated with p-type Bi_0.4Sb_1.6Te₃ and n-type Bi₂Te₃ thin films. The generator consisted of 20 pairs of p-type and n-type legs. We demonstrated complex structures of different conduction types of thermoelectric elements on the same substrate using two separate deposition runs of p-type and n-type thermoelectric materials. To demonstrate power generation, we heated one side of the sample with a heating block and measured the voltage output. An estimated power of 1.3 μW was obtained for the temperature difference of 45 K. We provide a promising procedure for fabricating thin film thermoelectric generators by using MOCVD grown thermoelectric materials that may have a nanostructure with high thermoelectric properties.     

Defect Characterization in Ge/(001)Si Epitaxial Films Grown by Reduced-Pressure Chemical Vapor Deposition

We studied the microstructural characteristics and electrical properties of epitaxial Ge films grown on Si(001) substrates by x-ray diffraction, atomic force microscopy, and transmission electron microscopy. The films were grown using a two-step technique by reduced-pressure chemical vapor deposition, where the first step promotes two-dimensional growth at a lower substrate temperature. We observed a decrease in defect density with increasing film thickness. Ge films with thickness of 3.5 μm exhibited threading dislocation densities of 5 × 10⁶ cm^?2, which yielded devices with dark current density of 5 mA cm^?2 (1 V reverse bias). We also noted the presence of stacking faults in the form of lines in the films and establish that this is an important defect for Ge films grown by this deposition technique.     

MOCVD法制备MgZnO合金薄膜

采用金属有机化学气相沉积方法在C面蓝宝石衬底上生长MgxZn1-xO合金薄膜.c轴取向的MgxZn1-xO薄膜在600.～630℃温度下沉积.通过X射线衍射和透射光谱研究了薄膜的结构和光学特性.研究表明当x的取值小于等于0.39时,合金薄膜保持ZnO的六角形纤锌矿结构,没有观察到MgO分相,此时薄膜的能带宽度可以在3.3～3.95eV之间调节.     

MOCVD法制备MgZnO合金薄膜

采用金属有机化学气相沉积方法在C面蓝宝石衬底上生长MgxZn1-xO合金薄膜.c轴取向的MgxZn1-xO薄膜在600～630℃温度下沉积. 通过X射线衍射和透射光谱研究了薄膜的结构和光学特性. 研究表明当x的取值小于等于0.39时，合金薄膜保持ZnO的六角形纤锌矿结构，没有观察到MgO分相，此时薄膜的能带宽度可以在3.3～3.95eV之间调节.     

MOCVD法制备MgZnO合金薄膜

采用金属有机化学气相沉积方法在C面蓝宝石衬底上生长MgxZn1-xO合金薄膜.c轴取向的MgxZn1-xO薄膜在600.～630℃温度下沉积.通过X射线衍射和透射光谱研究了薄膜的结构和光学特性.研究表明当x的取值小于等于0.39时,合金薄膜保持ZnO的六角形纤锌矿结构,没有观察到MgO分相,此时薄膜的能带宽度可以在3.3～3.95eV之间调节.     

等离子增强化学汽相淀积a-SiC:H簿膜的AES研究

用俄歇电子能谱(AES)对等离子增强化学汽相淀积(PECVD)氢化非晶碳化硅(a-SiC∶H)薄膜进行了组分的深度剖析、半定量分析以及化学分析.俄歇深度剖析曲线表明PECVD淀积的薄膜均匀性非常好;用俄歇半定量结果比较了薄膜成分同淀积工艺参量之间的一些关系;根据实验获得的Si LVV和CKLL俄歇谱比较和讨论了不同[Si]/[C]浓度比薄膜的化学特征.     

InAlN薄膜MOCVD外延生长研究

为了研究不同压力和不同模板对InA lN薄膜外延生长的影响,分别选取以GaN为模板时生长压力为4.00、6.67和13.33 kPa,压力为4.00 kPa时模板为GaN和A lN这两组条件进行实验比较。研究发现,随着生长压力的增加,样品中In含量降低,样品的粗糙度则随压力的增加而增大;压力为4.00 kPa时,分别以摇摆曲线半高宽(FWHM)为86.97″的A lN和224.1″的GaN为模板,发现A lN模板上生长的InA lN样品(002)和(102)峰的FWHM值及表面粗糙度比上述GaN为模板生长的InA lN样品都要小很多。综合以上结果可初步得知:降低压力可以优化InA lN薄膜的表面形貌,增加In组分含量;采用高质量的A lN作模板能生长出晶体质量和表面形貌都比较好的InA lN薄膜。     

GaN1-xPx三元合金的MOCVD生长

用金属有机化学气相淀积技术在蓝宝石衬底上成功外延了高P 组分的GaN1-xPx三元合金.俄歇电子能谱深度剖面结果表明在GaN1 -xPx中P的掺入量最高达到20%且分布均匀;X射线光电子能谱价态分析证实了外延层中Ga-P键的存在.对不同P组分的GaN1-xPx样品进行了低温光致发光 (PL)测试,与来自GaN衬底的带边发射相比,随三元合金中P组分的变化,GaN1-x Px的PL峰呈现出了不同程度的红移.在GaN1-xPx的PL谱中没有观测到有关GaP的发射峰,表明该合金材料没有发生相分离.     

InAIN薄膜MOCVD外延生长研究

为了研究不同压力和不同模板对InAlN薄膜外延生长的影响,分别选取以GaN为模板时生长压力为4.00、6.67和13.33 kPa,压力为4.00 kPa时模板为GaN和A1N这两组条件进行实验比较.研究发现,随着生长压力的增加,样品中In含量降低,样品的粗糙度则随压力的增加而增大;压力为4.00 kPa时,分别以摇摆曲线半高宽(FWHM)为86.97”的AIN和224.1”的GaN为模板,发现A1N模板上生长的InAIN样品(002)和(102)峰的FWHM值及表面粗糙度比上述GaN为模板生长的InAlN样品都要小很多.综合以上结果可初步得知:降低压力可以优化InAlN薄膜的表面形貌,增加In组分含量;采用高质量的AIN作模板能生长出晶体质量和表面形貌都比较好的InAlN薄膜.     

AlGaN材料的MOCVD生长研究

文章研究了AlGaN材料的MOCVD生长机制。在位监控曲线表明,AlGaN材料生长过程是由三维生长逐渐过渡到二维生长,由于Al原子表面迁移率太小,随着TMAl流量的增加,需要更长的时间才能出现二维生长,材料质量也随着Al组分的增加而下降,AlGaN的表面形貌也变差。随着TMAl流量的增加,AlGaN材料的生长速率反而下降,这是由于Al原子阻止了Ga原子参与材料生长。实验还发现,由于TMAl与NH3 之间存在强烈的寄生反应,AlGaN材料中的Al组分远小于气相中的Al组分。文中简单探讨了提高AlGaN材料质量的生长方法。     

GaN1-xPx三元合金的MOCVD生长

用金属有机化学气相淀积技术在蓝宝石衬底上成功外延了高P 组分的GaN1-xPx三元合金.俄歇电子能谱深度剖面结果表明在GaN1 -xPx中P的掺入量最高达到20%且分布均匀;X射线光电子能谱价态分析证实了外延层中Ga-P键的存在.对不同P组分的GaN1-xPx样品进行了低温光致发光 (PL)测试,与来自GaN衬底的带边发射相比,随三元合金中P组分的变化,GaN1-x Px的PL峰呈现出了不同程度的红移.在GaN1-xPx的PL谱中没有观测到有关GaP的发射峰,表明该合金材料没有发生相分离.     

金属有机化学气相沉积生长的GaN膜中V缺陷研究

利用金属有机化学气相沉积(MOCVD)技术,在Si(111)衬底上外延生长不同厚度的GaN。外延层薄的GaN表面存在大量的V缺陷,并且V缺陷的两侧有相互平行的带状高坡;外延层厚的GaN表面没有V缺陷,表面平整且晶体质量高。位错处存在晶格畸变,杂质易于在此处聚集,达到一定浓度就会抑制晶体在此处生长而形成V缺陷。受位错附近应力场与气流的影响,V缺陷两侧出现带状高坡。生长时间延长,GaN表面的V缺陷就会被填满,带状高坡横向生长合并成为平整的表面。用m(KOH)∶m(H2O)=1∶10的KOH溶液腐蚀后,平整的表面出现六角腐蚀坑,密度与原生坑密度相近,认为是原生坑被填满的位置腐蚀后再次出现。     

Millimeter-Size All-inorganic Perovskite Crystalline Thin Film Grown by Chemical Vapor Deposition

The chemical vapor deposition (CVD) method is a dry approach that can produce high quality crystals and thin films at large scale which can be easily adapted by industry. In this work, CVD technology is employed to grow high quality, large size all-inorganic cesium lead bromide perovskite crystalline film for the first time. The obtained films have millimeter size crystalline domains with high phase purity. The growth kinetics are examined in detail by optical microscopy and X-ray diffraction. The deposition rate and growth temperature are found to be the key parameters allowing to achieve large scale crystal growth. The large crystalline grains exhibit exceptional optical properties including negligible Stokes shift and uniform photoluminescence over a large scale. This suggests a high degree of crystallinity free from internal strain or defects. A lateral diode within one large crystalline grain is further fabricated and significant photo-generated voltage and short circuit current are observed, suggesting highly efficient carrier transport and collections without scattering within the grain. This demonstration suggests that the CVD grown all-inorganic perovskite thin films enable a promising fabrication route suitable for photovoltaic or photo-detector applications.     

Characteristics and Electrical Properties of SiNx: H Films Fabricated by Plasma-Enhanced Chemical Vapor Deposition

SiNx:H films with different N/Si ratios are synthesized by plasma-enhanced chemical vapor deposition (PECVD). Composition and structure characteristics are detected by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It indicates that Si-N bonds increase with increased NH3/SiH4 ratio. Electrical property investigations by I-V measurements show that the prepared films offer higher resistivity and less leakage current with increased N/Si ratio and exhibit entirely insulating properties when N/Si ratio reaches 0.9, which is ascribed to increased Si-N bonds achieved.     

Characteristics and Electrical Properties of SiNx：H Films Fabricated by Plasma-Enhanced Chemical Vapor Deposition

SiNx：H films with different N/Si ratios are synthesized by plasma-enhanced chemical vapor deposition （PECVD）. Composition and structure characteristics are detected by Fourier transform infrared spectroscopy （FTIR） and X-ray photoelectron spectroscopy （XPS）. It indicates that Si-N bonds increase with increased NH3/SiH4 ratio. Electrical property investigations by I-V measurements show that the prepared films offer higher resistivity and less leakage current with increased N/Si ratio and exhibit entirely insulating properties when N/Si ratio reaches 0.9, which is ascribed to increased Si-N bonds achieved.     

Multilayered Ge/SiGe Material in Microfabricated Thermoelectric Modules

Results for low dimensional p-type Ge/SiGe superlattices with Ge quantum wells of 3.43 nm are presented. A range of microfabricated test structures have been developed to characterise the cross-plane electrical and thermal properties of the Ge/SiGe heterostructures. These superlattices were directly grown on 100-mm-diameter silicon wafers by a chemical vapour deposition growth system with rates up to 6 nm/s. Quantum well and quantum mechanical tunnel barriers with dimensions down to \(\sim1\) nm have been designed, grown and tested; they demonstrate a ZT of 0.08 ± 0.011 and power factor of 1.34 ± 0.15 m W m^?1 K^?2 at 300 K. A complete microfabricated module using indium bump-bonding is reported together with preliminary results on unoptimised material and leg dimensions. Routes to optimise the material and modules are discussed.     

Mg掺杂的AlGaN的MOCVD生长

文章主要研究利用金属有机物化学汽相沉积（MOCVD）方法制备的Mg掺杂AlGaN薄膜。根据Raman光谱对Mg掺杂AlGaN薄膜应力和X射线摇摆曲线对晶体质量的研究表明引入高温AlN插入层能有效调节应力，并提高薄膜质量，降低位错密度。实验发现在保持Mg掺杂量不变的情况下，随着Al组分的上升，材料中出现大量岛状晶核，粗糙度变大，晶体质量下降，由三维生长向二维生长的转变更加困难。同时研究发现Al组分的上升和Mg掺杂量的增加都会使得螺位错密度上升；Mg的掺杂对于刃位错有显著影响，而Al组分的上升对刃位错无明显影响。经过退火温度对空穴浓度影响的研究，发现对于P型Al0.1Ga0.9N样品，900℃为比较理想的退火温度。     

Mg掺杂的AlGaN的MOCVD生长

文章主要研究利用金属有机物化学汽相沉积(MOCVD)方法制备的Mg掺杂AlGaN薄膜.根据Raman光谱对Mg掺杂AlGaN薄膜应力和X射线摇摆曲线对晶体质量的研究表明引入高温AlN插入层能有效调节应力,并提高薄膜质量,降低位错密度.实验发现在保持Mg掺杂量不变的情况下,随着Al组分的上升,材料中出现大量岛状晶核,粗糙度变大,晶体质量下降,由三维生长向二维生长的转变更加困难.同时研究发现Al组分的上升和Mg掺杂量的增加都会使得螺位错密度上升;Mg的掺杂对于刃位错有显著影响,而Al组分的上升对刃位错无明显影响.经过退火温度对空穴浓度影响的研究,发现对于P型Al0.1Ga0.9N样品,900℃为比较理想的退火温度.     

Magnetic Properties of Fe-Implanted ZnO Nanotips Grown by Metal-Organic Chemical Vapor Deposition

Fe ions were implanted into well-aligned single-crystal ZnO nanotips grown on SiO₂/quartz substrates using metal-organic chemical vapor deposition (MOCVD). The Fe ion concentration distribution within a single nanotip is mapped by electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) and the nanotips imaged by high-resolution transmission electron microscopy (TEM). X-ray absorption spectroscopy (XAS) identified the presence of Fe²⁺ and Fe³⁺ ions in both as-implanted and annealed samples. However, Fe³⁺ ion concentration increased during postannealing. Superconducting quantum interference device (SQUID) measurements show that the as-implanted and postannealed ZnO nanotips are ferromagnetic at room temperature. The observed ferromagnetism in the as-implanted nanotips is primarily attributed to the near surface 10-nm region that has high Fe concentration. The saturation magnetization reduces after annealing.     

MOCVD生长不同Al组分AlGaN薄膜

本文研究了利用金属有机物化学汽相淀积系统(MOCVD)生长高质量不同Al组分AlxGa1-xN薄膜(0.13＜x＜0.8).扫面电子显微镜(SEM)照片表明生长的AlN插入层有效地调节了AlGaN层与GaN支撑层的应力,使AlGaN表面平整无裂纹,原子力显微镜(AFM)测量得到所有AlGaN薄膜粗糙度均小于1 nm.通过原位干涉谱发现,AlGaN薄膜生长速率主要由Ga流量大小控制,随Al组分升高逐渐降低.利用X射线衍射和卢瑟福背散射(RBS)两种方法确定AlGaN薄膜的Al组分,发现Al组分与摩尔比TMAl/(TMGa+TMAl)关系为线性,说明在优化的生长条件下,Al原子与NH3的寄生反应得到了有效的抑制.