AuGeNi—n型GaAs欧姆接触界面微区结构与接触电阻率的关系

欧姆接触是砷化镓器件中的基本单元，它的电性能极大地影响器件的质量。在众多的欧姆接触系统中，ＡｕＧｅＮｉ系统应用最为广泛。利用扫描俄歇电子微探针对离子注入重掺杂的ｎ型ＧａＡｓ上利用快速热合金制备的ＡｕＧｅＮｉ欧姆接触进行了研究，比较了不同退火温度下欧姆接触的电性能和微区界面结构，对界面微区结构与接触电阻的关系进行了探讨，提出了产生低阻接触的理想微区结构，为工艺参数的选择提供了有益的依据。     

Pressure dependence of the thermal contact resistance for rough surfaces

The contact resistance is expressed analytically as a function of load for elastic and elastoplastic contacts by taking the rough surface as consisting of spherical projections with a normal distribution.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 1, pp. 62–67,July, 1970.     

单层有机发光二极管中复合区域和外量子效率的研究

建立了单层有机电致发光器件复合区域和外量子效率的模型,讨论了外加电压与器件厚度对复合区域和外量子效率的影响.结果表明(1)器件的复合区域宽度随着电场强度的增加而减小;(2)随着外加电压的升高,器件的外量子效率先增加后减小.     

Thermal contact resistance estimation: influence of the pressure contact and the coating layer during a hot forming process

The Thermal Contact Resistance R _C Estimation constitutes an encountered problem to be resolved in any forming process. To fairly simulate a part cooling during a hot stamping process, an experimental device was designed and developed by the Laboratoire de Thermocinétique de Nantes—France in collaboration with ArcelorMittal R&;D Montataire—France. The object is to estimate the thermal contact resistance at the part/tool interface during the three stage of the hot stamping process. During hot stamping phases, different contact types occur at the part/tool interface. The forming phase is characterized by a dynamic contact due to the increasing effort applied by the punch. At the contact interfaces, thermal contact resistances R _C are estimated experimentally through a non-linear 1D inverse technique founded on sequential method of Beck. Experiments were carried out on hot stamping samples made of Usibor 1500P® and 22MnB5 galvanized steel. The range of prospected stamping pressure varies from 10 to 30?MPa. The analysis of the effort curves shows the same mechanical resistance law of the part during the forming phase, whatever the consign effort settled to reach the maximum stamping pressure. The R _C value estimated for the galvanized steel is 33% lower than the one estimated for Usibor 1500P®. It is due to a higher harmonic thermal conductivity of the coated material. Results have been established as correlation of type: R _C ?=?f(P) to be used for numerical simulation.     

Examination of the dependence of adsorption of water and anions on metals on the potential by the contact electric resistance method

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 2, pp. 3–12, March–April, 1990.     

Reducing the contact resistance of SiNW devices by employing a heavily doped carrier injection layer

Silicon nanowires (SiNWs) are promising building blocks for future electronic devices. In SiNW-based devices, reducing the contact resistance of SiNW-metal as much as possible is critically important. Here we report a simple fabrication approach for SiNW field effect transistors (FETs) with low contact resistances by employing a heavily doped carrier injection layer wrapped around SiNWs at the contact region. Both n- and p-type SiNW-FET devices with carrier injection layers were investigated, the contact resistances were one order smaller than those without carrier injection layers and only contribute less than 14.8% for n-type devices and 11.4% for p-type devices, respectively, to the total resistance. Such low contact resistance guarantees the device characteristics mainly from the channel region of SiNW-based devices.     

Investigation of charge trapping and breakdown characteristics of sputtered-Y2O3 on n-GaAs substrates

Metal-oxide-semiconductor (MOS) capacitors fabricated by depositing yttrium oxide (Y₂O₃) using radio frequency sputtering system on top of n-GaAs substrates have been investigated. To study the interface properties, charge trapping behavior and breakdown characteristics of Y₂O₃ gate dielectric, the MOS capacitors were subjected to constant current stress, high pulse voltage stress and high constant voltage stress. The average value of the cross section of generated traps during electrical stress has been determined from our experimental data. Further the trap charge density, its distribution and location have been investigated by measurements on application and subsequent withdrawal of high pulse voltage stress. Additionally, stress induced leakage current density and time dependent dielectric breakdown characteristics have been obtained and time-to-breakdown exceeding 840 s is observed for Y₂O₃ gate dielectrics directly deposited on n-GaAs. Our experimental results have been analyzed with simple analytical formulae available in the literature.     

外加偏压对未退火Co/n-poly-SiGe肖特基接触特性的影响

采用直流离子束溅射法,在n型单晶硅衬底上淀积Si1-xGex薄膜.俄歇电子谱(AES)测得Si1-xGex薄膜的Ge含量约为0.15.对薄膜进行高温磷扩散后,经XRD测试为多晶态,即得n-poly-Si0.85Ge0.15.在n-poly-Si0.85Ge0.15上溅射一层薄的Co膜,做成Co/n-poly-Si085Ge0.15肖特基结样品.在90～332 K范围对未退火样品做I-V-T测试.研究发现,随着外加偏压增大,表观理想因子缓慢上升,肖特基势垒高度(SBH)下降.基于SBH的不均匀分布建模,得到了二者近似为线性负相关的结论.     

Improvement of Ge/Pd/GaAs ohmic contact by In layer

The presented work describes behaviour of contact structures of the Ge/Pd type with the In layer deposited on the surface of the GaAs substrate plate prior to the metallization. The most suitable structure by contact resistivity and thermal stability is Ge(40 nm)/Pd(20 nm)/In(22 nm). This structure shows minimal contact resistivity 2 × 10⁻⁶ Ωcm². Raman spectroscopy and XPS spectroscopy was used for the contact structure analysis. After thermal annealing, the metallization contains GePd phase and a thin germanium layer remains at the surface. Very slight reaction of indium with the substrate (creation of a ternary phase InGaAs) has been proved. Germanium and palladium diffuse into the GaAs substrate, the surface layer of GaAs is doped by Ge and Pd is built in the GaAs crystal structure instead of arsenic.     

Hydrogen passivation studies in Pd/n-GaAs devices

The effect of hydrogen on the current (I-V) and capacitance (C-V, TSCAP) has been studied for Pd/n-GaAs diodes. Hydrogenation has been found to improve ideality factor of the diode. ReverseC-V characteristics show that the number of shallow and deep donors is reduced on hydrogenation. The TSCAP measurement shows the presence of two donor states at ∼ 0.48 and 0.72 eV which is being partially passivated on hydrogenation. The likely origin of these states is discussed.     

Investigation of contact resistance between silicon and silver paste made by screen-printing

In this paper, the front contact resistance of screen-printing crystalline silicon solar cells was investigated. By establishing a fine model for silicon and silver paste contact made by screen-printing and fire-through, the three kinds of conduction mechanism were analyzed quantitatively. According to the model, the comprehensive calculation of the contact resistance between silicon and silver paste sintering was made for the first time. The results calculated in this study suggest that the contact resistance of silicon and silver paste is about 1.20 mΩ for 125 mm × 125 mm single crystalline silicon solar cells, this approximately agrees with the measured values. By optimizing composition of silver paste according to our results, the silver consumption per watt can be reduced, and the efficiency of crystalline silicon solar cells can be further improved. The results laid the foundation for studying the screen-printed crystalline silicon solar cell front contact metallization system.     

Investigation on the intermetallic compound layer growth of SnZnGa/SnZnGaNd solder joints

Growth kinetics of intermetallic compound layers (IMCs) formed between SnZnGa/SnZnGaNd solders for re-flow soldering and Cu substrate during aging was investigated at temperatures between 100 and 150 °C. The Cu₅Zn₈ IMCs could be found by reacting SnZnGa/SnZnGaNd solders on Cu substrate, and it was found that the addition of rare earth Nd can decrease the thickness of the IMCs of SnZn/Cu solder joints. The apparent activation energies of Cu₅Zn₈ which were calculated as 48.76 kJ/mol (SnZnGa) and 56.99 kJ/mol (SnZnGaNd). The shear force of Sn9Zn0.5Ga0.08Nd solder joint after aging treatment was remarkably higher than those of Sn–9Zn and Sn9Zn0.5Ga solder joints. The results would provide support to the superiority of Sn9ZnGaNd solder which can be used in the electronic packaging instead of traditional SnPb solder.     

Measurement of metal/carbon nanotube contact resistance by adjusting contact length using laser ablation

A technique of measuring contact resistance between an individual nanotube and a deposited metallic film is described. Using laser ablation to sequentially shorten the contact length between a nanotube and the evaporated metallic film, the linear resistivity of the nanotube as well as the specific contact resistivity between the nanotube and metallic film can be determined. This technique can be generally used to measure the specific contact resistance that develops between a metallic film and a variety of different nanowires and nanotubes.     

Dependence of the contact heat conductivity of granular systems on the external load

An examination has been made of the dependence of the contact heat conductivity of granular systems on the external load. The calculation formulas proposed for contact heat conduction are applicable over a wide range of materials.Notation s_a area of actual contact of two particles in a granular material - _c conductivity of the contact between two particles - h_r height of a micro-roughness - _s thermal conductivity of the material of the particles - d=2r particle diameter - _c contact thermal conductivity of the granular material - p porosity of the system - S_a1, S_a2 area of contact of two particles in the freely poured state and under the action of a load - f thermal conductivity of the granular system in the freely poured state - () portion of the thermal conductivity of a granular material that depends on the external load - relative area of contact - s_n nominal area of contact of the two particles - external specific load - E modulus of elasticity of the particle material - E₀ effective modulus of elasticity of the granular material - k₁, k₂, k₃, k_m, k_b empirical coefficients     

Distance dependence of the Surface Enhanced Raman Scattering effect observed in amorphous TiO2 on nanostructured gold

Plasmon resonance of gold nanoparticles is responsible of the electromagnetic (EM) Surface Enhanced Raman Scattering (SERS) effect. Interaction of an amorphous matrix with a SERS substrate was studied. Thin films with different thickness of amorphous TiO₂ coated on a Klarite® substrate show a 100 times enhancement of the Raman signal. Distance dependence of the SERS interaction was shown to be less than 60 nm.