金辅助催化方法制备GaAs和GaAs/InGaAs纳米线结构的形貌表征及生长机理研究

利用金（Au）辅助催化的方法,通过金属有机化学气相沉积技术制备了GaAs纳米线及GaAs/InGaAs纳米线异质结构.通过对扫描电子显微镜（SEM）测试结果分析,发现温度会改变纳米线的生长机理,进而影响形貌特征.在GaAs纳米线的基础上制备了高质量的纳米线轴、径向异质结构,并对生长机理进行分析.SEM测试显示,GaAs/InGaAs异质结构呈现明显的“柱状”形貌与衬底垂直,InGaAs与GaAs段之间的界面清晰可见.通过X射线能谱对异质结样品进行了线分析,结果表明在GaAs/InGaAs轴向纳米线异质结构样品中,未发现明显的径向生长.从生长机理出发分析了在GaAs/InGaAs径向纳米线结构制备过程中伴随有少许轴向生长的现象.     

4 K photoluminescence characterization of silicon implanted GaAs

GaAs technology for microwave devices (MESFET and MMIC) has received a significant improvement by ion implantation of silicon to form n-type active channel regions. Owing to amphoteric behaviour of silicon in GaAs, different activation of the implanted species can be obtained, depending on the post-implantation annealing treatment. In this paper we describe the results of the influence of rapid thermal annealing on implanted GaAs and using 4 K photoluminescence spectroscopy we identify the corresponding species (Si_AS and Si_AS-V_AS complex) in silicon doped GaAs and explain the electrical behaviour of the implanted and annealed material.     

Controlling boron diffusion during rapid thermal annealing with co-implantation by amphoteric impurity atoms

A model for simulating the rapid thermal annealing of silicon structures implanted with boron and carbon is developed. The model provides a fair approximation of the process of boron diffusion in silicon, allowing for such effects as the electric field, the impact of the implanted carbon, and the clustering of boron. The migration process of interstitials is described according to their drift in the field of internal elastic stress.     

Front and back surface cw CO2-laser annealing of arsenic ion-implanted silicon

The annealing behavior of arsenic-implanted silicon under scanned cw CO₂-laser irradiation from front and back surfaces is investigated. Ellipsometry, Hall effect, Rutherford backscattering measurements and neutron activation analysis indicate an enhancement of annealing efficiency by laser irradiation from the back surface, which provides complete recovery of crystal damage, high substitutionality and electrical activation of implanted arsenic atoms without redistribution of concentration profile. The enhancement of annealing efficiency under back-surface irradiation is explained by the difference in laser reflection from the front and back surface of silicon wafers. No differences in the results are found for scanned and static annealing.     

Iron contamination in ion implanted silicon,as revealed by x-ray and electron diffraction

A surface contamination effect was detected by double-crystal x-ray diffraction analysis of silicon wafers implanted with silicon ions at different doses and energies after annealing at 700 °C.The hypothesis of recoiled oxygen from the native oxide, as the impurity responsible for surface strain, was excluded by x-ray characterization of a series of samples implanted through thermally grown silicon oxides. The surface positions of the strain, resulting from x-ray analysis after 700 °C annealing and the analysis of the electron diffraction patterns, taken on particles originated from precipitation of the impurity by 1000 °C heating, allowed to conclude that the contamination phenomenon is due to iron atoms coming from the ion implanter.     

Laser annealing of radiation defects in low disordered layers

Abstract

Carrier concentration and mobility dependences on the annealing temperature have been compared for the cases of thermal (10 min) and laser (8 ms) annealing of silicon, implanted with low doses of P⁺ ions. It was found that the recovery of concentration and mobility depended on the heating time in different ways. The laser annealing requires higher temperatures for mobility recovery then the thermal treatment. The same temperature shift was observed for increase of carrier concentration but only after doses less than 3.10¹²m^?2. When the doses exceeded 3.10¹² cm^?2 laser and thermal annealing resulted in equal electron concentrations providing the equality of heating temperatures. Annealing of disordered regions was accounted for the mobility recovery. The increase of electron concentration was explained as an instantaneous decay of defect-impurity complexes. To check the validity of the assumptions laser annealing of electron and light ions irradiated materials was investigated.     

离子辐照对单晶Si中预注入B原子扩散的影响

室温下使用MeV能量级Si,F和O离子对5keV B离子预注入后的n-型单晶Si(100)进行了辐照,应用二次离子质谱仪测试分析了掺杂物B原子的分布剖面及其变化.结果表明,高剂量Si,F和O离子的附加辐照可以抑制热激活退火中B原子发生的瞬间增强扩散.在相同的辐照条件下,Si近表面区域中SiO₂层的存在更有助于限制B原子的瞬间增强扩散.结合卢瑟福沟道背散射分析和DICADA程序计算对实验结果进行了讨论.     

铝诱导非晶硅薄膜的场致低温快速晶化及其结构表征

铝诱导非晶硅薄膜晶化可以降低退火温度、缩短退火时间，是制备多晶硅薄膜的一种重要方法.在此基础上，通过在退火过程中加入电场加速了界面处硅、铝原子间的互扩散，实现了非晶硅薄膜的快速低温晶化.实验结果表明，外加电场，退火温度为400℃，退火时间为60min时，薄膜的晶化率大于60％；退火温度为450℃退火时间为30min时，薄膜已经呈现明显的晶化现象；退火温度为500℃退火时间为15min时，薄膜的x射线多晶峰强度与非晶峰强度之比为未加电场的3—4倍. 关键词： 非晶硅薄膜 多晶硅薄膜 外加电场     

Thermal quenching of photoluminescence in ZnO/ZnMgO multiple quantum wells following oxygen implantation and rapid thermal annealing

The temperature-dependent photoluminescence in oxygen-implanted and rapid thermally annealed ZnO/ZnMgO multiple quantum wells is investigated. A difference in the thermal quenching of the photoluminescence is found between the implanted and unimplanted quantum wells. Oxygen implantation and subsequent rapid thermal annealing results in the diffusion of magnesium atoms into quantum wells and thus, leads to an increased fluctuation in the potential of the quantum wells and the observation of a large thermal activation energy. However, a high dose of implantation results in large defect clusters and thus an additional nonradiative channel, which leads to a flat potential fluctuation and a small thermal activation energy.     

Processing for optically active erbium in silicon by film co-deposition and ion-beam mixing

Techniques of film deposition by co-evaporation, ion-beam assisted mixing, oxygen ion implantation, and thermal annealing were been combined in a novel way to study processing of erbium-in-silicon thin-film materials for optoelectronics applications. Structures with erbium concentrations above atomic solubility in silicon and below that of silicide compounds were prepared by vacuum co-evaporation from two elemental sources to deposit 200-270 nm films on crystalline silicon substrates. Ar⁺ ions were implanted at 300 keV. Oxygen was incorporated by O⁺-ion implantation at 130 keV. Samples were annealed at 600 °C in vacuum. Concentration profiles of the constituent elements were obtained by Rutherford backscattering spectrometry. Results show that diffusion induced by ion-beam mixing and activated by thermal annealing depends on the deposited Si-Er profile and reaction with implanted oxygen. Room temperature photoluminescence spectra show Er³⁺ transitions in a 1480-1550 nm band and integrated intensities that increase with the oxygen-to-erbium ratio.     

Parallel microwave chemistry in silicon carbide reactor platforms: an in-depth investigation into heating characteristics

The heating behavior of silicon carbide reaction platforms under 2.45 GHz microwave irradiation was investigated with the aid of online thermoimaging cameras and multiple-channel fiber-optic probe temperature sensors placed inside the wells/vials of the silicon carbide microtiter plates. Microwave irradiation leads to a rapid and homogeneous heating of the entire plate, with minimal deviations in the temperature recorded at different positions of the plate or inside the wells. In temperature-controlled experiments using dedicated multimode reactors, solvents with different microwave absorption characteristics can be heated in parallel in individual wells/vials of the silicon carbide plate reaching the same set temperature. Due to the large heat capacity and high thermal conductivity of silicon carbide, the plates are able to moderate any field inhomogeneities inside a microwave cavity. Although the heating of the plates can be performed extremely efficiently inside a microwave reactor, heating and synthetic applications can alternatively be carried out by applying conventional conductive heating of the silicon carbide plates on a standard hotplate. Due to the slower heating of the silicon carbide material under these conditions, somewhat longer reaction times will be required.     

Location of 125I implanted in silicon and germanium

A Mössbauer study of ¹²⁵I implanted into silicon and germanium lattices with various dose values was performed. The spectra measured after thermal annealing suggested an off-substitutional site population for I in the silicon lattice. The Mössbauer spectra showed no difference in the hyperfine splitting of ¹²⁵Te after electron capture of ¹²⁵I in comparison with that obtained after the isomeric transition of implanted ^125mTe. The site populations of Te and I atoms after implantation and thermal annealings were concluded as being the same.     

Thermally induced quantum well shape modification in strained heterostructures

We have demonstrated that shallow ion (⁷⁵As⁺) implantation and rapid thermal annealing (RTA) of strained InGaAs/GaAs quantum well (QW) structures can modify the optical properties of these epitaxial semiconductor heterostructures in a spatially selective manner. After RTA, QW exciton energies, determined from peaks in the photoluminescence spectra, shifted significantly to higher values only in the implanted regions. The magnitudes of the shifts were dependent on QW widths, RTA temperatures, and ion implantation fluences. The shifts were interpreted as arising from the modification of the shapes of the as-grown QWs from square (abrupt interfaces) to rounded (gradual interfaces) due to enhanced indium diffusion out of the well layers in irradiated areas as a consequence of the in-diffusion of vacancies generated near the surface by the implantation. Except for QWs near the critical thickness boundary, the presence of strain in the quantum well layers due to the difference in the lattice constant of the well and barrier layers had negligible effect on the QW shape modification due to thermal processing.     

Interaction between antimony atoms and micropores in silicon

The interaction between Sb atoms and micropores of a getter layer in silicon is studied. The getter layer was obtained via implantation of Sb⁺ ions into silicon and subsequent heat treatment processes. The antimony atoms located in the vicinity of micropores are captured by micropores during gettering annealing and lose its electrical activity. The activation energy of capture process to the pores for antimony is lower than that of antimony diffusion in silicon deformation fields around microvoids on the diffusion process.     

磷化铟中铁原子替位与填隙的热致转变及其对材料性质的影响

高温退火后掺铁半绝缘(SI)InP单晶转变为n型低阻材料.利用霍尔效应(Hall)，热激电流谱(TSC)，深能级瞬态谱(DLTS)，X射线衍射等方法分别研究了退火前后InP材料的性质和缺陷.结果表明受高温热激发作用部分铁原子由替位转变为填隙，导致InP材料缺少深能级补偿中心而发生导电类型转变.通过比较掺杂、扩散和离子注入过程Fe原子的占位和激活情况分析了这一现象的机理和产生原因. 关键词： 磷化铟 铁激活 退火 半绝缘     

Extended defect removal in silicon by rapid thermal annealing

Summary Germanium, arsenic and krypton ions of 600 keV energy were implanted in <100> silicon substrate at 250°C. The hot implantation results in the formation of extended defects (dislocation loops and cluster of point defects) as residual damage. Rapid thermal annealing process at a temperature above 1000°C was used to remove the damage. Rutherford-backscattering channelling technique was used to measure the amount of defects and their annealing. In some cases the channelling results were correlated to transmission electron microscopy (TEM) analysis. The annealing process of the damage is governed by an activation energy of (4.4±0.2) eV for both germanium and arsenic implants. During RTA processes broadening of the As and Ge distributions is quite negligible. The Kr atoms interact instead with defects and the annealing even after a prolonged time at 1100°C is not complete, bubbles surrounded by extended defects are left The authors of this paper have agreed to not receive the proofs for correction.     

Activation of Al2O3 passivation layers on silicon by microwave annealing

Thin aluminum oxide layers deposited on silicon by thermal atomic layer deposition can be used to reduce the electronic recombination losses by passivating the silicon surfaces. To activate the full passivation ability of such layers, a post-deposition annealing step at moderate temperatures (≈400 ^°C, duration≈30 min) is required. Such an annealing step is commonly done in an oven in air, nitrogen, or forming gas atmosphere. In this work, we investigate the ability to reduce the duration of the annealing step by heating the silicon wafer with a microwave source. The annealing time is significantly reduced to durations below 1 min while achieving effective minority carrier lifetimes similar or higher to that of conventionally oven-annealed samples.     

高性能自持燃烧的氘氚等离子体

在等离子体密度分布一定的情况下，从电子、离子的能量输运方程出发，对常规剪切和中心负剪切位形下高性能自持燃烧的氘氚等离子体进行了研究.常规剪切下采用与能量约束改善因子H有关的Bohm热传导系数，中心负剪切下采用一个与磁剪切有关的Bohm-gyro-Bohm混合型的热传导系数，并考虑了α粒子反常扩散和动态反馈加热对氘氚自持燃烧的影响.研究结果表明，常规剪切下当H≥3时，才有较大的能量输出，当H接近4时无须动态反馈加热氘氚就能获得自持燃烧；在中心负剪切位形下，等离子体的运行性能更高，有更高的能量输出，一旦氘氚达 关键词： 高性能等离子体 氘氚自持燃烧 中心负剪切     

Laser crystallization for large-area electronics

Laser crystallization is reviewed for the purpose of fabrication of polycrystalline silicon thin film transistors (poly-Si TFTs). Laser-induced rapid heating is important for formation of crystalline films with a low thermal budget. Reduction of electrically active defects located at grain boundaries is essential for improving electrical properties of poly-Si films and achieving poly-Si TFTs with high performances. The internal film stress is attractive to increase the carrier mobility. Recent developments in laser crystallization methods with pulsed and continuous-wave lasers are also reviewed. Control of heat flow results in crystalline grain growth in the lateral direction, which is important for fabrication of large crystalline grains. We also report an annealing method using a high-power infrared semiconductor laser. High-power lasers will be attractive for rapid formation of crystalline films over a large area and activation of silicon with impurity atoms.     

Annihilation kinetics of defects induced by phosphorus ion implantation in silicon

Ion channeling and electrical characterization techniques have been used in order to study the effects of thermal annealing on phosphorus implanted silicon wafers. A low energy thermally activated process (0.15–0.28 eV) is clearly observed after annealing at low temperature (≤500 °C). This electrical activation mechanism is found to be well described by a local relaxation model involving point defect migration. It is shown that in order to achieve a complete electrical activation of the implanted impurities, an annealing must be performed at temperatures higher than 700 °C.