Separation of Mid-IR Light Trapping and Sulfur-Donor Absorption in Nanosecond-Laser Sulfur-Hyperdoped Silicon: a Way to Spatially- and Spectrally-Engineered Interband IR-Absorption

We perform IR nanosecond laser microtexturing and hyperdoping of commercial silicon wafers under a 5 mm thick carbon-disulfide liquid layer at broadly variable laser exposures from incomplete to multi-shot irradiation per spot. All these samples demonstrate that the mid-IR-range optical densities and sulfur-donor dopant vary concentrations nonmonotonously versus laser intensity and scanning speed due to surface ablation and its vapor bubble screening. This enabled us, for the first time, to distinguish the predominating MIR-light trapping in microstructured Si at high exposures and a characteristic sulfur-donor MIR-absorption at lower exposures at rather constant sulfur concentrations. The characteristic interband sulfur-donor IR-absorption exhibits increasing magnitude for larger dissolved sulfur clusters versus increase in total sulfur concentration, paving the way for spatially- and spectrally-engineered MIR-absorption in hyperdoped Si for thin-film photovoltaics.     

Nucleation,Growth, and Aggregation of Au Nanocrystals on Liquid Surfaces

We report the formation of gold ramified aggregates after deposition of Au on an ionic liquid surface by thermal evaporation method at room temperature.It is observed that the aggregates are composed of both granules and nanocrystals with hexagonal or triangular appearances.The most probable size of the nanocrystals is much larger than that of the granules and it increases with the nominal deposition thickness.The formation mechanism of the granules,nanocrystals and aggregates is presented.     

基于机械-化学的方法在硅表面制造功能化结构

"利用机械与化学结合的方法在芳烃重氮盐溶液中用金刚石刀具切削硅片,使得芳香烃分子和硅之间以共价键连接,实现了对硅片的"成形并功能化"的一步完成．研究了在大气环境如何利用金刚石刀具在硅表面加工出表面质量较好的微结构,为下一步在溶液中"成形并功能化"硅提供好的基底．在溶液中对硅表面进行可控自组装实验,初步研究了切削速度和组装时间对切削处生成自组装膜质量的影响,总结出较适合膜生长的参数．用X射线光电子能谱对自组装膜进行了检测,用扫描电子显微镜和原子力显微镜对自组装膜的表面形貌进行了表征,并用原子力显微镜对自     

Mechanism of Diffusion of Carbon and Silicon Monooxides in a Cubic Silicon Carbide Crystal

Physics of the Solid State - The main processes that occur during diffusion of gaseous carbon CO and silicon SiO monoxides through a layer of a single-crystal silicon carbide SiC of the cubic...     

分光光度法快速测定碳钢中的硅、锰和磷

通过一次称量、溶样,采用分光光度法分别测定了普碳钢及低合金钢中硅、锰、磷的含量。实验表明,该方法操作简便、快速、准确度高,重现性好。     

室温下掺Er富硅氧化硅和掺Er富硅氮化硅的光致发光及其退火

用磁控溅射淀积掺Er氧化硅、掺Er富硅氧化硅、掺Er氮化硅和掺Er富硅氮化硅薄膜,室温下测量这四种薄膜的光致发光（PL）谱,观察到这四种薄膜都具有1.54μm的峰位,其强度与薄膜的退火温度有关。为了确定1.54μmPL的最佳退火温度,这些薄膜都分别在600,700,800,900,1000,1100℃的温度下同时退火,发现两种富硅薄膜的最佳退火温度是800℃,不富硅的两种薄膜的最佳退火温度是900℃。样品的1.54μmPL最强,且800℃退火的掺Er富硅氧化硅薄膜的1.54μm峰强度是最强的,比不富硅的强了约20倍,还观察到这四种薄膜都具有1.38μm的PL带,且掺Er富硅氧化硅和掺Er富硅氮化硅这两种薄膜的PL在强度上1.38μm峰与1.54μm峰有一定的关系。     

Condensation Behavior of Ag Aggregates on Liquid Surfaces

We report a condensation behavior of silver aggregates on silicone oil surfaces. The deposited Ag atoms diffuse and aggregate on the oil surface, and then form granular clusters and ramified islands. The apparent Ag coverage of the total area increases linearly with the nominal film thickness h for h 〈 0.9nm. However, the coverage exhibits a fluctuation behavior for 1.0 nm 〈 h〈 2.5 nm. It is found that the anomalous behavior of the coverage is resulted from a characteristic material condensation process in the aggregates.     

Structure Sensitive Reaction Channels of Molecular Hydrogen on Silicon Surfaces

The ability of the Si(001) surface to adsorb H2 molecules dissociatively increases by orders of magnitude when appropriate surface dangling bonds are terminated by H atoms. Through molecular beam techniques the energy dependent sticking probability at different adsorption sites on H-precovered and stepped surfaces is measured to obtain information about the barriers to adsorption, which decrease systematically with an increase in coadsorbed H atoms. With the help of density functional calculations for interdimer adsorption pathways, this effect is traced back to the electronic structure of the different adsorption sites and its interplay with local lattice distortions.     

Anisotropic Fermi Surfaces,Electrical Transport,and Two-Dimensional Fermi Liquid Behavior in Layered Ternary Boride MoAlB

We report a study of fermiology,electrical anisotropy,and Fermi liquid properties in the layered ternary boride MoAlB,which could be peeled into two-dimensional（2 D） metal borides（MBenes）.By studying the quantum oscillations in comprehensive methods of magnetization,magnetothermoelectric power,and torque with the firstprinciple calculations,we reveal three types of bands in this system,including two 2 D-like electronic bands and one complex three-dimensional-like hole band.Meanwhile,a large out-...     

Microstructure and Magnetic Domains of Iron Films on Liquid Surfaces

Iron （Fe） films with a thickness ranging from 1.Onto to 80.Onto are deposited on silicone oil surfaces by a vapor phase deposition method. The films with a thickness old 〈 2.0 nm do not exhibit planar morphology but ramified aggregates instead. Magnetic force microscopy studies for the Fe films （10.0nm ≤d ≤ 80.0nto） show that the domain wall structure is widespread and irregularly shaped and the oscillation phase shift △θ, which records as the magnetic force image, changes from 0.29°to 0.81°. Correspondingly, the magnetic force gradient varies from 1.4 ×10^-3 to 4.0× 10^-3 N/m, respectively. In our measurement, the characteristic domain walls, such as Bloch walls, Neel walls and cross-tie walls, are not observed in the film system clearly.     

Effect of Pulsed Laser Annealing on Optical Properties of Selenium-Hyperdoped Silicon

Optics and Spectroscopy - Layers of selenium-hyperdoped silicon with dopant concentration of up to (4–6) × 1020 cm–3 that exceeds the limit of equilibrium solubility of this...     

退火温度对富硅氮化硅薄膜发光特性和结构的影响

采用直流等离子体增强化学气相沉积(PECVD)法在(100)单晶硅片表面生长富硅氮化硅薄膜,研究了不同的退火温度对氮化硅薄膜发光性质和结构的影响。研究发现,随着退火温度的升高,氮化硅薄膜的发光强度逐渐减弱,发光是由缺陷能级引起的,在900 ℃时荧光基本消失。XPS测试表明,在N₂氛围900 ℃下退火,氮化硅薄膜中未有硅相析出,故未表现出硅量子点的发光。FTIR测试也为PL结论提供了一定的证据。     

Functionalization of Individual Multi-Wall Carbon Nanotubes during Irradiation and Annealing

Physics of the Solid State - The structure of individual multi-wall carbon nanotubes exposed to irradiation by a argon ions and electron flux, as well as subsequent heat processing in an inert...     

Dynamic Scaling of Ramified Clusters Formed on Liquid Surfaces

A comprehensive simulation model -deposition,diffusion, rotation, reaction and aggregation model is presented to simulate the formation processes of ramified clusters on liquid surfaces, where clusters can diffuse and rotate easily. The mobility (including diffusion and rotation) of clusters is related to its mass, which is given by Dm = Dos-γD and θm =′θos-γθ, respectively. The influence of the reaction probability on the kinetics and structure formation is included in the simulation model. We concentrate on revealing dynamic scaling during ramified cluster formation. For this purpose, the time evolution of the cluster density and the weight-average cluster size as well as the cluster-size distribution scaling function at different time are determined for various conditions. The dependence of the cluster density on the deposition flux and time-dependence of fractal dimension are also investigated. The obtained results are helpful in understanding the formation of clusters or thin film growth on liquid surfaces.     

Dynamic Scaling of Ramified Clusters Formed on Liquid Surfaces

A comprehensive simulation model -- deposition, diffusion, rotation, reaction and aggregation model is presented to simulate the formation processes of ramified clusters on liquid surfaces, where clusters can disuse and rotate easily. The mobility （including diffusion and rotation） of clusters is related to its mass, which is given by Dm = Dos^-γD and θm = θos^-γθ, respectively. The influence of the reaction probability on the kinetics and structure formation is included in the simulation model. We concentrate on revealing dynamic scaling during ramified cluster formation. For this purpose, the time evolution of the cluster density and the weight-average cluster size as well as the cluster-size distribution scaling function at different time are determined for various conditions. The dependence of the cluster density on the deposition flux and time-dependence of fractal dimension are also investigated. The obtained results are helpful in understanding the formation of clusters or thin film growth on liquid surfaces.     

Polarity Reversal of Terahertz Electric Field from Heavily p-Doped Silicon Surfaces

Above-band-gap optical excitation of electron-hole pairs screens the doping-induced surface electric field and generates terahertz(THz) pulses via free-carrier transport. THz emission from a heavily doped silicon surface is much weaker than that of lightly doped samples. A polarity reversal of the THz electric field is observed in heavily doped p-type silicon, indicating that the doping related and carrier induced surface electric fields oppose each other. By comparing the penetration depth of the excitation laser with the thickness of the depletion layer for the doped silicon, it is shown that competition between diffusion and drift current causes the polarity reversal.     

退火及溅射气氛对氮化硅薄膜光致发光的影响

利用射频磁控反应溅射方法制备富硅的氮化硅薄膜。衬底材料为抛光的硅片,靶材为硅靶,在Ar-N₂气环境下,通过改变两种气体的组分比来改变样品成分,并在高纯N₂气氛下对其进行高温退火处理。用X射线光电子能谱(XPS)和X射线衍射(XRD)对样品进行了表征,并测试了样品的光致发光谱 (PL)。实验结果表明：X射线光电子能谱中出现了Si—N键合结构,同时还有少量的Si—O键生成,通过计算得出Si/N比值约为1.51,制备出了富硅的氮化硅薄膜;薄膜未经退火前,在可见光区域没有观察到明显的光致发光峰,经过高温退火后,XRD中新出现的衍射峰证实了纳米硅团簇的生成,PL图谱中在可见光区域出现了光致发光峰的蓝移现象,结合XRD结果,用纳米晶的量子限域效应对上述现象进行了合理解释。     

红外碳硫测定仪分析等外金属硅中碳

利用红外碳硫测定仪，探索了等外金属硅中碳金属含量的测定方法，对助溶剂的种类，用量及样品的用量等实验条件进行了优化选择，测定快速，结果准确。     

表面钝化对多晶硅绒面形貌的影响

多晶硅表面制绒技术是太阳能光伏产业亟待突破的一个关键技术.本文根据多晶硅强酸制绒的基本原理,提出了表面活性剂钝化多晶硅表面以降低硅原子与酸反应速度从而改善多晶硅绒面形貌的方法.实验研究了不同含量的添加剂对酸液刻蚀多晶硅绒面形貌的影响,用扫描电镜观察对应的绒面结构,用积分反射仪测量其绒面的表面反射率.实验结果表明:加入活性剂后酸液能使多晶硅表面陷阱坑分布更加均匀,并且能有效消除产生漏电流的缺陷性深沟槽,样品表面反射率比较低,其表面反射率降低到21.5%.与传统酸液腐蚀的多晶硅绒面结构相比,陷阱坑密度明显增加,这种方法在多晶硅太阳电池的生产中是有价值的.