Space charge and light generation in SrS:Ce thin filmelectroluminescent devices

Transient light and charge-voltage measurements on SrS and SrS:Ce thin film electroluminescent devices have been carried out with triangular voltage bursts after illumination. The observations indicate that the trailing edge emission is due to electrons which are emitted from the anodic interface as soon as the field there changes sign and recombine effectively with ionized Ce atoms. From charge-voltage measurements the space charge in the phosphor layer is estimated to be two times higher for the Ce doped sample. Due to this sample charge the field in the phosphor layer of the SrS:Ce devices decreases dramatically from the cathodic toward the anodic interface. If the field at the anodic interface is close to zero, efficient light emission will arise from recombination of electrons with ionized Ce atoms in this region     

Electrical characterization and modeling of alternating-currentthin-film electroluminescent devices

Electrical characterization of evaporated ZnS:Mn alternating-current thin-film electroluminescent (ACTFEL) devices is accomplished by capacitance-voltage (C-V) analysis. Interpretation of these C-V characteristics is aided by SPICE modeling and by electrical characterization of an ideal ACTFEL device constructed from discrete components, based on a simple equivalent circuit for the ACTFEL device. Various features of the C -V curve are ascribed to equivalent circuit parameters and associated device physics parameters     

Electrical modeling of compound semiconductor interface for FET device assessment

A unified model for GaAs and InP metal-insulator-semiconductor (MIS) systems is presented. It involves particular types of U-shaped distributions of interface states, localized and nonlocalized states, and tunneling processes. Detailed experimental data including theC-Vdata, frequency dependence of MIS admittance, photocapacitance transient spectroscopy, and deep-level transient spectroscopy, support the model. Formation of a disordered nonstoichiometric semiconductor region is suggested to be the most probable mechanism for the anomalous distributions of interface states. Effects of interface states on microwave MISFET's, and implications of the model for logic applications are briefly discussed.     

Molecularly derived mesoscale modeling of an epoxy/Cu interface: Interface roughness

This paper addresses use of coarse-grained mesoscale model to look at angle dependencies in an epoxy–copper (I) oxide interface in order to understand roughness effects on adhesion. The parameterizations of the coarse-grained beads were previously calculated from the molecular level ,  and  for the same polymer and copper oxide interface. Roughness was investigated in two ways: applying a zigzag interface to the interface separation simulation, and separating the interface using differing angles. When compared, both methods reduce to the similar energy trends. In addition, the effect moisture on the interface was compared for the rough and smooth interfaces.     

Mobility analysis of surface roughness scattering in FinFET devices

This paper presents a mobility analysis of the surface roughness scattering along the different interfaces of FinFET devices. Using temperature dependent analysis of effective mobility, quantitative information about the influence of the roughness could be obtained directly on the device. The sidewall and top surface drain current components were estimated from the total drain currents of different fin width conditions. Using a conventional mobility model, it was possible to fit the gate voltage and temperature dependence of sidewall and top surface mobilities. This procedure allowed the contribution of the surface roughness scattering to be quantified with nondestructive characterization. Significant differences were observed for sidewalls and top surface. In the specific case under study, surface roughness scattering on sidewalls was about three times stronger than on top surface for n-channel FinFETs, whereas it remained similar for p-channel ones.     

Effects of oxide interface traps and transient enhanced diffusionon the process modeling of PMOS devices

We present a model which simulates the trapping of arsenic and boron dopants at the silicon-silicon dioxide interface, and demonstrate that this model gives significantly more accurate doping profiles for a wide range of PMOS devices, as characterized by the device Threshold Voltage. In addition, a newly-developed Transient Enhanced Diffusion (TED) model is applied for the first time to the process simulation of buried-channel PMOS devices, predicting an enhanced Short Channel Effect and Drain Induced Barrier Lowering (DIBL) effect. By using both these models, an excellent agreement is achieved between simulated and measured device characteristics for PMOS devices with gate lengths varying from 2 to 0.4 μm, over a wide range of bias conditions and operating temperatures     

Electrical characterisation of transferred-electron devices

A technique is presented that enables the chip admittance of stable t.e.d.s (t.e.a.s) to be determined accurately in any microwave circuit. An extension of the technique for the characterisation of oscillating t.e.d.s (t.e.o.s) is discussed.     

Unified modeling of field-effect devices

This paper describes a unifying approach to the derivation of models for field-effect devices. The most general model yielded by this approach contains, as special cases, models for the small- and large-signal behavior of the two major types of field-effect transistor and of other related devices such as the semiconductor current limiter and the pinch resistor. From this most general model emerge, by application of particular approximations and constraints, several models proposed earlier for use in computer- aided circuit analysis. The unifying approach thus demonstrates the relationships borne among various existing models for field- effect devices. In addition, it provides a wide diversity of new models of different complexities and degrees of accuracy.     

多层介质薄膜膜层间界面粗糙度及光散射

利用泰勒霍普森相关相干表面轮廓粗糙度仪(Talysurf CCI)分别对基底和采用电子束热蒸发技术沉积的15层二氧,化钛(TiO2)和二氧化硅(SiO2)为膜料的介质高反膜的膜层间的界面粗糙度进行了研究,并对不同工艺下沉积的薄膜界面粗糙度以及不同基底粗糙度上沉积的薄膜的表面粗糙度进行了比较.实验结果表明:TiO2薄膜对基底或下表面粗糙度有较好的平滑作用,随着TiO2和SiO2膜层的交替镀制,膜层间表面粗糙度呈现出低高交替的现象,随着膜层层数的增加,膜层间界面粗糙度低高变化范围减小;采用离子束辅助沉积工艺时,膜层问界面粗糙度低高变化范围较小.总散射损耗的理论计算表明:中心波长处完全非相关模型下的总散射损耗小于完全相关模型下的总散射损耗.实验结果表明:界面粗糙度的相关度约为0.4.     

Deuterium passivation of interface traps in MOS devices

The mechanism for deuterium passivation of interface traps in MOS devices is studied. Normal channel hot electron (CHE) stress was performed on hydrogen-passivated devices to locally desorb hydrogen from the interface at the drain region. The stressed devices were annealed in deuterium at 400°C, resulting in a full recovery of device characteristics. These devices were then subjected to CHE stress again in two modes. Some of them were stressed in the normal mode while others were stressed in the reverse mode in which the source and drain were interchanged. Compared with hydrogenated devices, these deuterated devices under the normal stress exhibit a significant reduction in interface trap generation and threshold voltage shift. In contrast, insignificant reliability improvement was observed for the reverse stress case. The asymmetric degradation behaviors on these deuterated devices suggest that the effectiveness of implementing deuterium to improve device reliability is limited by its replacement of pre-existing hydrogen at the oxide/silicon interface     

Statistical modeling of reliability in logic devices

Due to continuous technology scaling VLSI circuits feature an increasing susceptibility to transient faults. While complete elimination of errors cannot be guaranteed, current mitigation techniques based on circuit improvement or architectural measures cause a large overhead in terms of area and energy consumption. A more efficient possibility to cope with transient faults can be to tolerate hardware errors at low physical levels and handle them at higher system levels. This can be achieved by reusing error handling capabilities – such as channel decoders – or introducing specialized error correction blocks that take advantage of the system characteristics by concentrating the effort on the components and bits most crucial for system operation. To enable this approach the influence of hardware errors on system performance needs to be evaluated, requiring spatial and temporal models of error propagation in the system. Since Monte Carlo simulation of complex systems is not feasible, a statistical modeling technique of logic gates and circuits is introduced. This approach allows modeling of noise and variability influences on logic gates as well as correlation due to reconvergent fan-out with an error of 5% compared to Monte Carlo simulation but with considerably less runtime.     

Electrical fluctuations in silicon double injection devices

Studies of the electrical noise behavior of indium-doped silicon P⁺πN⁺ double injection devices are reported. The work refers to the double injection portion of the device characteristic at a temperature of 77°K. The noise studied is attributed to fluctuations in the rate of recombination of carriers via the indium centers. From fitting theoretical and experimental results, the carrier lifetime is found to be 2.5 × 10⁻⁷ sec and the capture cross-section of neutral indium centers for electrons is determined to be 1.8 × 10⁻¹⁶ cm².     

Electromagnetic modeling of organic light-emitting devices

Based on the rigorous electromagnetic wave theory, a numerical model for simulating the radiation characteristics of organic light-emitting devices (OLEDs) is developed. In particular, a novel method for overcoming the numerical difficulty in taking the thick glass substrate into account is proposed. The numerical results confirm the importance of the effects of the thick glass substrate. The algorithms based on the numerical model are then used for evaluating the dependencies of OLED radiation characteristics on various parameters, including the thickness of different device layers and the cathode metal variety. In the study of the effect of emission layer (EML) thickness, it is found that the radiation spectral peak red shifts with increasing EML thickness. This trend is consistent with the experimental result.     

Mechanical modeling of flexible OLED devices

General expressions are deduced for the stresses developed in the individual thin layers of a multi-layer structure as a result of bending to a specified radius. These are appropriate for analysing flexible organic light emitting diode (FOLED) devices on flexible substrates. Residual stress (caused internally by temperature change and differential thermal expansion) after material deposition and return to ambient temperatures is not considered. The reduced elastic modulus of the typical small molecule OLED materials: N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine (NPD) and tris-(8-hydroxyquinoline)aluminum (Alq₃) are measured as thin-films using nano-indentation techniques. A conventional device: polyethylene terephthalate (PET)/Buffer layer (BL)/ITO/OLED/Al is considered from a modeling standpoint, as a preliminary to actual fabrication and subsequent comparative testing of OLED performance on rigid and flexible supports.     

Numerical modeling of magnetic-field-sensitive semiconductor devices

Semiconductor devices in the presence of a magnetic field have been modeled numerically. The two-dimensional distributions of the electric potential, the electron concentration, and the hole concentration in a silicon slab exposed to a magnetic field have been computed. We have generalized the well-known Scharfetter-Gummel scheme to the case of two dimensions and nonzero magnetic field and employed a finite-difference technique. Our results are in support of earlier results in case of Hall plates. In intrinsic or closely intrinsic silicon, our results show both magnetoconcentration and space-charge effects. As a realistic example of a magnetic-field sensor, we have modeled a p⁺-i-n⁺silicon diode with split contacts.     

Mo基底的粗糙度对C轴择优取向AlN的影响

通过物理气相沉积的方法制备出Si／非晶／Mo／AlN多层膜器件,利用透射电子显微学方法研究了截面样品和AlN薄膜平面样品,确定了AlN和 Mo的界面形态和生长方式。研究表明二者取向关系为[2110] AlN／／[111]Mo,（0002）AlN／／（110）Mo,且Mo表面的粗糙程度对AlN的生长有影响,因此本文为改进器件性能提供了参考方向。     

Electrical contacts for II-VI semiconducting devices

High resistivity II-VI semiconductors in general and CdTe and its associated materials like CdZnTe and CdMnTe in particular are suffering from ohmic contacting problem due to their high electron affinity and consequently large work function. Ni, Au, Pt and Pd have large work function and have possibility to match with the above materials. However, except Ni other materials have problems in large-scale commercial applications. In order to overcome the ohmic contacting problem to these semiconductors the following studies has been conducted in the text of the present paper. These are: (i) Work function engineering to modulate the work function through combination materials like, Cu, Au, Mo, W and Co. (ii) Introduction of a charge diluting intermediate semiconducting layer media in between the metal and CdTe to neutralize the bound polarized charges. These two aspects were applied in case of thin film CdTe-CdS solar cells to evaluate their contacting performances and their influences in solar cell parameters. Both cell performances and the contact characteristics of these contacting technologies were studied at depth and indicated their applicability in semiconducting devices.     

面向开关过程的大功率电力电子器件建模

传统的大功率电力电子装置仿真中,通常将电力电子装置的开关动态过程视为理想过程,不能如实反映工作过程中的电压电流尖峰脉冲对系统的影响,针对该问题文章提出了一种面向开关过程的大功率电力电子器件建模方法,运用插值建模的方法,对大功率电力电子器件进行兼顾全面性和细致性的仿真,正确反映开关动态过程中大功率电力电子器件过程中的电压电流尖峰现象,从而获得较高的仿真精度。     

Rigorous modeling of high-speed semiconductor devices

We present a review of industrial heterostructure devices based on SiGe/Si and III–V compound semiconductors analyzed by means of numerical simulation. A comparison of device simulators and current transport models is given and critical modeling issues are addressed. Results from two-dimensional hydrodynamic analyses of heterojunction bipolar transistors (HBTs) are presented in good agreement with measured data. The examples are chosen to demonstrate technologically relevant issues which can be addressed by device simulation.     

Numerical modeling of vertical Hall-effect devices

A two-dimensional numerical simulation of the unconventional Hall device recently proposed by Popovic is presented. Some improved and simplified alternative device structures are proposed and simulated as well.