Schottky barrier SOI-MOSFETs with high-k La(2)O(3)/ZrO(2) gate dielectrics

Schottky barrier SOI-MOSFETs incorporating a La₂O₃/ZrO₂ high-k dielectric stack deposited by atomic layer deposition are investigated. As the La precursor tris(N,N′-diisopropylformamidinato) lanthanum is used. As a mid-gap metal gate electrode TiN capped with W is applied. Processing parameters are optimized to issue a minimal overall thermal budget and an improved device performance. As a result, the overall thermal load was kept as low as 350, 400 or 500 °C. Excellent drive current properties, low interface trap densities of 1.9 × 10¹¹ eV⁻¹ cm⁻², a low subthreshold slope of 70-80 mV/decade, and an I_ON/I_OFF current ratio greater than 2 × 10⁶ are obtained.     

Structural and electrical properties of ultra-thin high-k ZrO2 film on nitride passivated Ge(100) prepared by PEALD

The study of ultrathin ZrO₂ films grown on surface passivated germanium substrates by plasma enhanced Atomic Layer Deposition (PEALD) has been carried out. Nitride passivation has been used to form an interfacial layer between ZrO₂/Ge. The ultra-thin ZrO₂ film deposited with thickness of ~5.75 nm and refractive index of ~2.05 as observed through ellipsometry. The Ge3d, Zr3d, N1s and O1s are XPS core level spectra's confirm the formation of GeON and ZrO₂ ultra-thin films. The AFM results show the roughness of deposited films as low as 0.3 nm. The effect of post metallization annealing (PMA) on electrical properties of Au/Cr/ZrO₂/GeON/Ge capacitors has been investigated. The improvement in k value (~38) and an EOT value (~0.5 nm) after PMA on Ge/GeON/ZrO₂ stack has been observed. The flat band voltage and hysteresis of post metallization annealed devices has been reduced as compared to that of without PMA GeON/ZrO₂ stack.     

The variation of impurity ionization with doping in heavily doped germanium

Complete ionization of impurity atoms in semiconductors which is the most common engineering assumption is found to breakdown in the heavily doped condition [1]. Here a calculation of the degree of ionization in degenerate germanium for different doping concentrations is presented.     

Visualizing the doping profile of a silicon germanium HBT with polysilicon emitter using electron holography

Modern bipolar transistors use polysilicon emitters and an epitaxial grown silicon germanium (SiGe) base. For device optimization, both the SiGe base and the region of the diffused emitter is of special interest. In this paper, electron holography is applied to visualize and directly measure the two-dimensional distribution of the local potential in a high-performance SiGe heterojunction bipolar transistor. Special emphasis is put on investigating the region of the emitter diffused into the epitaxially grown base layer. In addition, we investigate the self-aligned base-link construction. We compare electron holographic measurements of the whole transistor to secondary ion mass spectrometric (SIMS) data and discuss the results.     

Performance of a two-link CPSK system incorporating direct phase regenerator with imperfect phase references

The letter analyses the performance of a two-link binary coherent phase-shift-keying (CPSK) communication system incorporating a direct phase regenerator (DPR) with imperfect carrier reference signals in the regenerator and the receiver. These references are extracted from the received signals by means of squaring loops. Additive Gaussian noise (AGN) is considered at the inputs of the DPR and the receiver.     

掺杂Fe_2O_3对氧化钒相变的影响

用电子陶瓷工艺制备了三种不同掺杂比例的临界热敏电阻CTR(Critical Temperature Resister),根据样品对应的热谱中的相变点,找出Fe2O3掺杂量与相变点的关系。从微观半导体理论分析晶粒体电特性,求解泊松方程,得出晶粒体中电势垒与受主杂质Fe2O3掺杂量的关系。结果表明:当x(Fe2O3)为10%～25%时,相变温度增加值?t和摩尔分数增加值(?x)2呈线性关系。     

Frequency Stabilization of Waveguide CO2 Laser by a Digital Technique

In this work we present a simple technique for laser frequency stabilization, based on Digital signal processing. The technique is used to stabilize a waveguide CO₂ laser of wide tunability by using three kinds of reference signals: the CO₂ laser ouptut power, an infrared absorption optoacoustic signal and the output power of a Far-Infrared optically pumped molecular laser.     

紫外激光刻蚀氧化锆陶瓷初步研究

描述了KrF准分子激光对氧化锆陶瓷的微刻蚀实验,研究了脉冲刻蚀深度与脉冲数的关系(刻蚀速率),刻蚀的槽的形貌,并进行了刻蚀小孔的初步研究,得到直径为40μm,深度为25μm的微孔矩阵。为KrF激光对该材料的加工提供实验数据。     

ZnO-V_2O_5系压敏电阻器的掺杂改性

用掺Ｂ２Ｏ３和Ｋ＋的方法改善ＺｎＯ－Ｖ２Ｏ５多元系压敏电阻器的性能。实验结果表明Ｂ２Ｏ３能起到液相促烧作用,同时也会影响材料的电性能。掺适量的Ｋ＋能改善漏电流、非线性系数等电性能。     

先驱体法制备PZT/ZrO2复合陶瓷材料

研究了一种新的制备PZT／ZrO2复合陶瓷材料的方法。借助B位先驱体法，首先合成亚稳态的钙钛矿固溶体，在高温下ZrO2相从固溶体中析出得到PZT／ZrO2复合陶瓷材料。在冷却过程中，已在PZT晶粒内析出的ZrO2相发生四方到单斜的相变，伴随该相变的体积膨胀会对晶界产生压应力，起到强化晶界的作用，从而使陶瓷材料的力学性能得到明显提高。     

Self-organization of germanium highly ordered nanoclusters by the deposition of polycrystalline silicon films doped with germanium

Aspects of the formation of self-organized clusters of germanium (Ge) and solid solution of SiGe, first formed in the mode of deposition of subthin polycrystalline silicon films doped with Ge on the nanoscale film of dielectrics were studied by techniques of atomic force microscopy and Raman scattering by optical phonons in germanium clusters. We found that in subthin polycrystalline silicon films (PSF) doped with Ge on the nanoscale films of dielectrics in conditions of PSF film deposition, there appeared correlated spatial distribution of germanium clusters, as well as silicon rich clusters in certain conditions, i.e., clusters of SiGe solid solution, with the modes of their formation. The relationship of the form, size, and density of Ge nanoclusters (NC), with the conditions of their self-organization is considered. The influence of interdiffusion processes on self-organizing of clusters is established, which is significant at high temperatures of the deposition and doping of PSF. It was found that clusters (islands) could occur on the cleavage surface in the form of four types of topographic features in a classical pyramid form, flat-topped pyramids, and domes and sharp spines, depending on the conditions of the deposition of PSF doped with Ge. The systems of highly organized Ge NC, measuring 3.5–40 nm and with a density of 2.7 × 10⁷–3.5 × 10 cm⁻² were obtained. The possibility, in principle, of managing the geometric parameters of self-organizing NC (nanoislands) by selecting the conditions of their self-organization in the mode of deposition of PSF doped with Ge, was shown.     

Improved manufacturability of ZrO2 MIM capacitors by process stabilizing HfO2 addition

A broad compositional range of the dielectric material Zr_1?xHf_xO₂ was evaluated with respect to its applicability in DRAM storage capacitors. The paper reports on phase composition, crystallization behavior, and electrical properties of the mixed system in planar metal-insulator-metal (MIM) capacitors. Admixture of HfO₂ into ZrO₂ proved to stabilize the deposition process at high temperatures without degrading the dielectric properties of the film. Compared to pure ZrO₂ the 30–40% HfO₂ containing films showed improved scalability (capacitance equivalent thickness 0.73 nm at 8 * 10^?9 A/cm²) as well as improved reliability.     

0.6nm-EOT high-k gate stacks with HfSiOx interfacial layer grown by solid-phase reaction between HfO2 and Si substrate

We have developed a process for forming an ultra-thin HfSiO_x interfacial layer (HfSiO_x-IL) for high-k gate stacks. The HfSiO_x-IL was grown by the solid-phase reaction between HfO₂ and Si-substrate performed by repeating the sequence of ALD HfO₂ deposition and RTA. The HfSiO_x-IL grown by this method enables the formation of very uniform films consisting of a few mono-layers, and the dielectric constant of the HfSiO_x-IL is about 7. The FUSI-NiSi/HfO₂ gate stacks with HfSiO_x-IL have achieved 0.6 nm EOT, a very low gate leakage currents between 1 A/cm² and 5 × 10⁻² A/cm², an excellent subthreshold swing of 66mV/dec, and a high peak mobility of 160 cm²/Vs compared to the reference samples without HfSiO_x-IL. These results indicate that the HfSiO_x-IL has a good quality compared to the SiO₂ interfacial layer grown by oxygen diffusion through HfO₂ films.     

SiO2和ZrO2薄膜光学性能的椭偏光谱测量

用溶胶-凝胶工艺在碱性催化条件下,采用旋转镀膜法在K9玻璃上分别制备了性能稳定的单层SiO2薄膜与单层ZrO2薄膜。用反射式椭圆偏振光谱仪测试了薄膜的椭偏参数,并用Cauchy模型对椭偏参数进行数据拟合,获得了溶胶-凝胶SiO2与ZrO2薄膜在300~800 nm波段的色散关系。用紫外-可见分光光度计测量了薄膜的透射率,并与用椭偏仪换算出来的结果相比较;用原子力显微镜观察了薄膜的表面微结构,并讨论表面微结构与薄膜光学常数之间的关系。分析结果表明,Cauchy模型能较好的描述溶胶-凝胶薄膜的光学性能,较详细的得到了薄膜的折射率,消光系数等光学常数随波长λ的变化规律;薄膜光学常数的大小与薄膜的微结构有关。     

Stabilization of 2D saturated systems by state feedback control

The problem of stabilizability of the 2D continuous-time saturated systems under state-feedback control is solved in this paper. Two cases are considered: the first one, the control may saturate and limits may be attained. The second one, the control does not saturate and limits are avoided. Sufficient conditions of asymptotic stability are presented. The synthesis of the required controllers is given under LMIs form. Illustrative examples are treated.     

掺杂Ag提升TiO_2纳米薄膜光电性能研究

采用sol-gel法制备出Ag掺杂的TiO_2纳米薄膜,利用SEM、XRD、UV-Vis、XPS及电化学工作站等对其光学及光电特性进行表征,研究了掺杂浓度及退火温度对材料晶体结构、光学特性及光电性能的影响规律。结果表明:Ag的掺杂提高了材料的晶相转变温度,降低了材料禁带宽度,使吸收带边发生红移(约40 nm),有效提高薄膜对太阳光的利用效率。当Ag掺杂浓度为摩尔分数0.5%,退火温度为500℃时,材料表现出最佳的光电活性,光电流密度达0.38×10~(–3)A/cm~2,相较于纯TiO_2薄膜的光电流密度增大约41%,光电性能得到显著提升且稳定性良好。     

Local doping of silicon by a point-contact microwave applicator

The feasibility of local doping in silicon by an open-end coaxial applicator with a tip made of the doping material, e.g. aluminum or silver, is studied in this paper. In these experiments, localized microwave power of 100-350 W at 2.45 GHz was applied for ∼1 min to obtain doped regions of ∼1-mm width and ∼0.3-μm depth. Independent measurements of secondary ion mass spectroscopy (SIMS) and junction built-in potential measured by atomic-force microscopy (AFM) were used to estimate the activated doping concentrations in the order of 10¹⁹ and 10²² cm⁻³ for aluminum and silver doping, respectively. Potential barriers (pn junctions) of 0.5-0.7 V were measured across the aluminum-doped regions, and I-V characteristics were observed. The doping experiments were conducted in air atmosphere, hence oxidation effects were observed as well. The localized-microwave doping concept presented here could be useful in small-scale semiconductor processes, integrated optics, and MEMS applications.     

溶胶-凝胶工艺ZrO2涂层工程陶瓷的界面结合机制

采用无机盐先驱体、溶胶－凝胶工艺在SG4工程陶瓷基体上成功制备了Z O2涂层。扫描电子显微镜,X射线衍射,二次离子质谱分析表明：涂层完整,晶粒均匀,主要成份为t-ZrO2;涂层与基体结合紧密,两者之间存在着明显的元素扩散。     

ZrO2 insulator modified by a thin Al2O3 film to enhance the performance of InGaZnO thin-film transistor

A high-performance InGaZnO (IGZO) thin-film transistor (TFT) with ZrO₂–Al₂O₃ bilayer gate insulator is fabricated. Compared to IGZO-TFT with ZrO₂ single gate insulator, its electrical characteristics are significantly improved, specifically, enhancement of I_on/I_off ratios by one order of magnitude, increase of the field-effect mobility (from 9.8 to 14 cm²/Vs), reduction of the subthreshold swing from 0.46 to 0.33 V/dec, the maximum density of surface states at the channel-insulator interface decreased from 4.3 × 10¹² to 2.5 × 10¹² cm⁻². The performance enhancements are attributed to the suppression of leakage current, smoother surface morphology, and suppression of charge trapping by using Al₂O₃ films to modify the high-k ZrO₂ dielectric.     

Modulation of the workfunction of Ni fully silicided gates by doping: dielectric and silicide phase effects

A systematic study of the modulation of the workfunction (WF) of Ni fully silicided gates by doping is presented, comparing the effects of dopants (Al, B, undoped, P, and As) on the WF for different dielectrics (SiO/sub 2/ versus HfSiON) and silicide phases (NiSi, Ni/sub 2/Si and Ni/sub 31/Si/sub 12/). Dual thickness series (HfSiON/SiO/sub 2/) were used to extract accurate WF values accounting for charge effects on HfSiON. While a WF modulation in the range of /spl sim/0.4 V was obtained for NiSi on SiO/sub 2/ comparing As, P, and B doped and undoped devices, negligible modulation was obtained for NiSi on HfSiON (/spl les/50 mV) suggesting Fermi-level pinning, and for the Ni-rich silicides on SiO/sub 2/ (/spl les/100 mV). Dopant pileup at the dielectric interface, believed to be responsible for the NiSi/SiO/sub 2/ WF modulation, was, however, observed for both NiSi and Ni-rich silicides. In contrast the WF of Ni-rich silicides on SiO/sub 2/ can be modulated with Al, suggesting a different mechanism of WF tuning for Al compared to B, P, and As.