Ion beam mixing for processing of nanostructure materials

Ion beam mixing (IBM) has been used to process various nanostructure materials and thin films for applications in microelectronics and optoelectronics. In this paper, a study of alloy formation of Si-Ge, processed at shallow depths followed by oxygen implantation, is presented. The mixture is annealed to form Si-GeO₂-Si, wherein the germanium oxide may form alone or as a matrix with the source of excitation. Characterization techniques used in this study include investigations of the structural variations due to argon ion-beam irradiation by Rutherford backscattering (RBS) and shallow defects and deep trapping level states by thermoluminescence (TL) measurements. Fourier transform infrared (FTIR) spectroscopy is used to analyze the thin film/islands of GeO₂ formed in the matrix.     

Electrical properties of rare earth silicides produced by channeled ion beam synthesis

Electrical measurements have been performed on ErSi_1.7, YSi_1.7 and Er_0.5Y_0.5Si_1.7, produced by channeled ion beam synthesis. The results have been compared with thin films of the same rare earth silicides produced by other methods. The room temperature resistivities of the ErSi_1.7, YSi_1.7 and Er_0.5Y_0.5Si_1.7 are 52, 69 and 87 μΩ cm, respectively, significantly higher than the reported values for MBE synthesised layers. The ErSi_1.7 shows evidence of magnetic ordering, but this is not observed in either the YSi_1.7 or the Er_0.5Y_0.5Si_1.7 down to 3 K.     

Optical and Magnetic Properties of ZnO:V Prepared by Ion Implantation

We report on the optical and magnetic properties of the magnetic semiconductor Zn(V)O fabricated by implantation of 195 keV ₅₁V⁺ ions into bulk ZnO:Al grown by a hydrothermal technique. Two sets of the samples, containing N _d –N _a ∼ 10¹⁵ cm⁻³ and 10¹⁸ cm⁻³, were implanted to doses of 1 × 10¹⁵ cm⁻², 3 × 10¹⁵ cm⁻², and 1 × 10¹⁶ cm⁻². The ion implantation was performed at 573 K. To remove irradiation-induced defects, the samples were annealed in air at 1073 K. Photoluminescence (PL) measurements of Zn(V)O films were carried out at temperatures from 10 K to 300 K. The effects of implantation dose and free carrier concentration on the magnetic properties of Zn(V)O were studied using a superconducting quantum interference device magnetometer. Ferromagnetism has been observed in annealed highly conductive samples implanted to 1 × 10¹⁶ cm⁻². The PL studies of ZnO bulk samples implanted with V⁺ have revealed that thermal annealing at 1073 K restores to a large extent the optical quality of the material. A new emission line centered at 3.307 eV has been found in the PL spectrum of the highly conductive samples implanted to the dose of 1 × 10¹⁶ cm⁻², which is most probably due to complexes involving V ions.     

离子束合成SIMOX技术的进展

综述了离子束科学技术领域新的重要进展－－从作为半导体掺杂手段的低剂量离子注入到高剂量离子注入合成新材料的离子束合成技术，讨论了高剂量注入的物理效应，介绍了利用高剂量氧注入硅合成ＳＩＭＯＸ材料的物理过程以及ＳＩＭＯＸ技术的多种应用，提出了提高ＳＩＭＯＸ材料性能的各种途径。     

离子注入对ITO薄膜电学特性的影响

对系列In2O3∶Sn (ITO)薄膜样品分别实施了不同剂量的Sn+, Ag+ 和Mo+离子注入并将它们在250 ℃下进行了热处理.利用霍耳测量研究了原始样品及注入和退火前后各样品的电学特性.研究了ITO薄膜的电学参数受离子注入的种类及剂量的影响.实验证明不同种类的离子注入会不同程度地降低ITO的导电性能,但热处理的效应与之相反.3种金属中,Sn+离子对薄膜造成的注入损伤最小,而高价的钼离子可以替换铟离子的位置成为施主,当注入剂量为1×1015 cm-2时,经过Mo+离子注入和后续退火的ITO薄膜,载流子浓度提高了14%.     

Structures and physical properties of sputtered amorphous SiC films

Optical and electrical properties have been measured for amorphous SiC films prepared by rf sputtering in a pure Ar atmosphere with a sintered 6H-SiC target. The absorption edge E₀ determined from the relation of αhΝ = B(hΝ-E₀)² ranged from 1.45 to 1.80 eV depending on the film thickness and the substrate temperature. The room temperature electrical conductivity is in the range of 5.4×10⁻¹¹ and 1.4×10⁻⁵ Ω⁻¹cm⁻¹. The absorption edge decreases and the conductivity increases with increasing film thickness. The absorption edge shifts to shorter wavelengths (blue shift) and the conductivity decreases during annealing below 400‡C for 60 min, whereas the absorption edge shifts to the longer wavelength side (red shift) and the conductivity increases during annealing at 800‡C It is proposed that the two annealing processes cause structural changes in amorphous SiC films, one of which involves removal of defects or voids while the other involves rearrangement or rebonding of the component atoms.     

LC—2A型离子注入设备的某些改进

本文叙述了弗里曼(Freeman)离子源体联接在LC-2A型中能离子注入机上的应用;表明了弗里曼离子源体与LC-2A型中能离子注入机光路系统相吻合后,可以茯得较大束流;这样,满足了我所半导体集成电路研制工艺中高剂量离子注入掺杂要求;文章还讨论了LC-2A型离子注入机束流增大后引起的诸如离子流的污染、磁分析器扁管防“穿通”、以及样品热聚积效应问题。     

A study of processed electronic materials containing inhomogeneous refractive index profiles

Processing of electronic materials often produces graded refractive index profiles near the surface, as for instance in ion-implanted and diffused semiconductors. Analysis of these materials by means of optical reflectance and transmittance measurements, simulations, and least-squares fits is prevalent, but cumbersome. In order to facilitate the nondestructive characterization of materials containing inhomogeneous layers, we developed new theoretical solutions in integral form for the reflectance and transmittance. Two special cases are emphasized in this paper: a buried Gaussian refractive index profile, and a transition region described by a half Gaussian. The analytical study of Gaussian profiles provides us with new methods for the direct estimation of the average depth x_p and the standard deviation σ from optical reflectance data. Our estimates of these parameters, derived from experimental reflectance data of ion-implanted silicon, germanium, and GaAs, agree well with the values estimated by means of elaborate curve-fitting procedures. Simulations performed by means of the well-known matrix method and our theory, not only show excellent agreement but also prove that our method is very time efficient. Therefore, this technique could be used advantageously as a diagnostic tool as well as in process controllers in the semiconductor manufacturing industry.     

离子注入硅形成绝缘埋层的红外反射谱分析

高剂量、大束流的O~+或N~+注入硅中经高温退火后能形成质量很好的SOI(Silicon onInsulater)材料。在波数范围为5000—1500cm~(-1)的红外波段内,硅及SiO_2或Si_3N_4绝缘埋层对红外光均无吸收。采用计算机模拟不同处理条件下的样品在该波段范围的红外反射谱,得到了样品的折射率随深度的变化关系,所得结果与透射电子显微镜、离子背散射等方法所得的分析结果符合得很好。     

Raman investigation of lattice defects in the CoSi2 synthesis using focused ion beam implantation

CoSi₂ layers were produced by 70 keV Co focused ion implantation into Si(111). Within a comparative study the CoSi₂ layer quality and implantation damage were investigated as a function of pixel dwell-time and substrate temperature. Irradiation damage measurements were done by micro-Raman analysis. The results suggest that the dwell-time dependence of the CoSi₂ layer formation — continuous layers for short and disrupted ones for long dwell-times — is caused by an accordant transition from crystalline to amorphous silicon.     

Improvement in Electrical Properties of SIMNI Films by Multiple-Step Implantation

SOI-SIMNI (Silicon On Insulator-Separation by Implanted Nitrogen) films were formed with standard method and multiple-step implantation one. The Hall-effect measurements (4-300K) show that the multiple-step implanted SIMNI films have a lower sheet resistance and higher carrier mobility than those in standard SIMNI films. The DLTS results indicate that there is a deep level defect (Et=0. 152 eV) in the standard SIMNI films but no such defects in the multiple-step implanted ones. The multiple-step implanted SIMNI films have good electrical properties.     

Improvement in Electrical Properties of SIMNI Films by Multiple-Step Implantation

In the past decade,there is an increasing interest in making Silicon-On-Insulator(SOI) films by high dose oxygen or nitrogen implantation into silicon,which will replaceSOS(Silicon-On-Sapphire) to fabricate the high-speed,no latch-up...     

Peculiarities of radiative recombination in amorphous molecular semiconductors doped with polymethine dye

Processes of charge carrier photogeneration and recombination are investigated in films of poly-N-epoxypropylcarbazole doped with polymethine dye. Films with blocking contacts were illuminated with light from either the region of dye absorption or beyond this region. The kinetics of accumulation and relaxation of electron–hole pairs with lifetimes greater than tens or hundreds of seconds was studied. It is presumed that the reason for the growth of recombination luminescence intensity in an external electric field is connected with the increase in efficiency of radiative recombination stimulated by electrons captured from photogenerated excitons. © 1998 John Wiley & Sons, Ltd.     

Dissociation of electron–hole pairs interacting with triplet excitons in amorphous molecular semiconductors

The photoconductivity of films of amorphous molecular semiconductors increases upon simultaneous photogeneration of singlet electron–hole pairs (EHPs) and triplet excitons and decreases upon photogeneration of triplet EHPs and triplet excitons. An increase in external electric field strength leads to a decrease in the effect of triplet excitons on the film photoconductivity caused by EHP dissociation. It is concluded that under increasing external electric field strength the mobility of charge carriers increases and the velocity of EHP dissociation becomes comparable with the velocity of spin conversion of EHPs interacting with triplet excitons. © 1997 John Wiley & Sons, Ltd.     

硅中离子注入硼的异常扩散

本工作用不同的Si~+预注入能量,改变注入损伤分布与离子注入硼杂质分布的相对位置,观察快速热退火中注入损伤对硼异常扩散的影响.结果表明,引起注入硼异常扩散的是点缺陷,而不是硼间隙原子的快扩散.而注入损伤中的点缺陷和簇团分解释放的点缺陷是驱动硼异常扩散的因素之一.如果注入损伤形成了扩展缺陷,那么扩展缺陷重构和分解将发射点缺陷,这是驱动硼异常扩散的另一个因素.     

多铁材料 Ni3V2O8的熔盐法制备与磁学性能

分别采用熔盐法和固相反应法制备了 Ni3V2O8多铁材料样品,并利用 X 射线衍射(XRD)、扫描电子显微镜(SEM)、能谱（EDS）、透射电子显微镜(TEM)、高分辨透射电镜（HRTEM）等表征手段分析了所得样品的物相、微观形貌及结构,并研究了其磁学性能。实验结果表明,采用熔盐法和固相反应法制备的 Ni3V2O8样品均为单一物相,呈正交对称型的晶体结构;熔盐法制备所得的样品呈棒状,颗粒直径约为 20 μm,长度约为 100 μm,单个晶粒呈明显的单晶特征;而固相反应法制备的 Ni3V2O8样品呈颗粒状,颗粒尺寸约为 25 μm,分布较均匀。熔盐法制备的 Ni3V2O8具有反铁磁性相变,相变温度在 3.6 K 左右,有效磁矩为 3.34 μB。     

离子注入中的沟道效应控制

离子注入中的沟道效应使注入离子在深度上的控制变得很困难，并使SHEET值的均一性恶化，本文借助计算机模型。对注入剂量，注入能量，硅片基板方位，硅片表面薄膜氧化层厚度变化时，研究分析了注入沟道效应的相应变化。     

用离子注入在GaAs中形成高浓度超薄有源层

高浓度浅结是高速砷化镓MESFET的重要技术.我们采用透过氮化硅薄膜进行Si离子注入的方法研制了载流子浓度大于10~(15)cm~(-3)的薄形有源层(<1000A).试验结果表明,氮化硅膜的厚度基本等于载流子浓度峰值位置向衬底表面移动的距离;高剂量(>10~(15)cm~(-2)),低能量,(<80keV)和较厚的氮化硅可以制得符合要求的薄形有源层.     

ZrW2O8/E-51电子封装材料电学性能研究

采用具有负热膨胀特性的ZrW2O8粉体和SiO2粉体分别作为填料制备E—51环氧树脂电子封装材料。测试了填料对封装材料的相对介电常数、介质损耗、阻温特性和电击穿场强等电性能的影响。结果表明:在相同含量下,ZrW2O8填料效果好;随ZrW2O8量的增加,介质损耗不断减小,ZrW2O8与E—51的质量比为0.7∶1时,相对介电常数最大;在室温~163℃范围内,ZrW2O8/E—51的电阻率稳定在3.03×106?.m,电击穿场强均大于10 kV/m。     

含左手材料和单负材料三层平板波导中TE模的传输特性

研究了以左手材料为衬底和单负材料为覆盖层三层平板波导中TE模的传输特性,为波导器件的设计提供理论支持。首先导出了归一化有效厚度H与归一化频率ν的关系,然后数值计算分析了三层平板波导的传输特性。结果表明,该三层平板波导TE模具有以下特性：1）当导波层与衬底或覆盖层磁导率的比值的增大时,归一化有效折射率b随频率ν的变化率减小。2）当不对称因子a趋近于0时,b随ν单调变化;当a较大时,在截止频率附近,TE₁、TE₂、TE₃、TE₄和TE₅模出现双值现象。3）当a增大时,H-ν曲线从左向右移动。4）对于TE₀模,H出现负值。