Numerical simulation of ion-exchange in glass for integratedoptical components

A numerical model based on the finite-element method for solving the nonlinear diffusion equation of ion-exchange in glasses is presented. The model is applied to the calculation of the concentration profile for a Ag⁺-Na⁺ ion-exchanged channel waveguide. The calculated concentration profile is in good agreement with a measured refractive-index profile of a waveguide fabricated with the same parameters as used in the calculations     

Study of aluminum thermomigration as a low thermal budget technique for innovative power devices

The main feature of the thermomigration of Al/Si liquid droplets in silicon for the realization of isolation walls in bi-directional power devices is its low thermal budget. Therefore, it is compatible with the utilization of epitaxial substrates for innovative power devices, for example, with reduced on-state resistance. This paper describes the design and realization of a medium power SCR on epitaxy. After structure presentation and voltage blocking capability simulation, the specific issue of thermomigration on (1 1 1)-orientated epitaxial substrates is considered. Limitations to migration are found due to the off-axis cut necessary for good epitaxial growth. Electrical characterization exhibits great agreement with simulation, demonstrating the great potential of thermomigration as a low thermal budget technique for isolation walls processing for both standard structures and new devices on epitaxy.     

Variable optical attenuator based on ion-exchange technology in glass

A thermooptic variable optical attenuator (VOA) based on the Mach-Zehnder interferometer principle was fabricated in glass by an ion-exchange technique. The thermooptical effect was reached via heating electrodes on the side of the Mach-Zehnder arms. The insertion loss of the device was 1 dB, the dynamic range was 38 dB, maximal power consumption was 138 mW, and the polarization-dependent loss (PDL) was 0.2 dB/0.6 dB at 10 dB/20-dB attenuations, respectively.     

Single-step buried waveguides in glass by field-assisted copper ion-exchange

Symmetric profile buried waveguides can be fabricated in glass by single-step electromigration of Cu/sup 2+/ ions from thin solid films. The theory of this process is given. The controllable process needs a molten multi-ionic anode to keep the glass surface background composition unchanged.<>     

Two-step channel selection-a novel technique for reconfigurable multistandard transceiver front-ends

This paper starts with a review of the prevailing channel-selection techniques utilized so far in the design of wireless transceiver analog front-ends before describing a novel two-step channel-selection technique, which handles the traditionally unwanted image, in radio frequency-to-intermediate frequency (RF-to-IF) or IF-to-RF frequency conversion, as a useful adjacent channel of the desired one, and selects deliberately either of them from IF to baseband (or baseband to IF). Thus, one more channel-selection possibility is created for both low-IF receivers and two-step-up transmitters. The consequential benefits of introducing channel selection at IF consist of two. First, many design specifications (such as phase noise and settling time) of the RF frequency synthesizer and local oscillator can be substantially relaxed. Second, a low-IF/zero-IF reconfigurable receiver and a direct-up/two-step-up reconfigurable transmitter can be synthesized to match better with narrowband-wideband-mixed multistandard systems. The operating principles of such architectures are presented in easy-to-understand complex-signal spectral-flow illustrations, and their practicability is demonstrated in the design of a Bluetooth/IEEE 802.11FH/HomeRF multistandard receiver. SPECTRE simulation results validate the reconfigurable functionalities mainly implemented by a triple-mode channel-select filter and a multifunctional sampling-mixer scheme.     

玻璃基离子交换型宽带22 3dB耦合器研究

为满足2N光功率分配器的制作和应用的需求,对宽带集成化22 3dB耦合器进行了深入的理论和实验研究。采用3-D光束传播法,对传统的非对称X结进行了模拟改进,设计了低损耗且具有较宽工作带宽的22 3dB耦合器。采用Ag+-Na+离子交换技术在玻璃基上成功制作了非对称X结结构的宽带22 3dB耦合器。通过对1260nm~1360nm和1460nm~1600nm两个波段宽带光源的光谱测试,得到在宽带范围内小于4.0dB的插入损耗,光谱谱线相对平坦,波长依赖性较小,均匀性小于0.5dB。结果表明,采用这种非对称X结并结合离子交换工艺,可以在玻璃基上制作出宽带的22 3dB耦合器,这为进一步优化器件性能,研制成功具有应用价值的器件奠定了基础。     

Novel tapping technique for charge-coupled devices

The letter proposes a useful technique for the nondestructive tapping of charge-coupled devices, with a presentation of both theoretical and experimental results for device operation. The usefulness of the technique lies primarily in its simplicity of fabrication and operation.     

Vacuum poling: an improved technique for effective thermal polingof silica glass and germanosilicate optical fibres

The use of thermal poling in a vacuum to eliminate the spreading out of the poled regions beyond the boundaries of the positive electrode is proposed and experimentally demonstrated. A substantial improvement in reproducibility and quality of the induced second-order susceptibility is achieved     

Phosphosilicate glass stabilization of FET devices

The threshold voltage of MOSFET devices can be effectively stabilized from changes due to field-assisted motion of Na⁺in the gate oxide by the addition of a phosphosilicate glass (PSG) layer. The effectiveness of the glass for this purpose is markedly enhanced by increasing the P2O5concentration of the PSG. However, polarization of the PSG layer can, in turn, cause an appreciable instability of the threshold voltage. It is shown that detailed knowledge of the behavior of PSG layers permits prediction of the threshold stability of P2O5-treated FET devices. Thus, threshold stability can be maintained to within 0.1 V/1000 Å under device operating conditions by making a proper compromise on PSG thickness and P2O5concentration. Such stabilizing films offer satisfactory protection against realistic Na⁺contamination levels. Quantitative data on these phenomena are presented, and a simple structural model is given to account for the polarization and the Na⁺trapping behavior of the films. The formation of PSG films by doping of SiO2with P2O5at elevated temperatures is discussed.     

Microjet cooling devices for thermal management of electronics

This research is an effort to demonstrate the applicability of miniaturized synthetic jet (microjet) technology to the area of thermal management of microelectronic devices. Synthetic jets are jets which are formed from entrainment and expulsion of the fluid in which they are embedded. Design issues of microjet cooling devices are discussed along with characterization of excitation elements and the turbulent synthetic jets produced thereby. Geometrical parameters of the microjet cooling devices were empirically optimized with regards to cooling performance. The cooling performance of the optimized microjets was compared with previous theoretical and empirical studies of conventional jet impingement. The cooling performance of the microjet devices has been investigated in an open environment as well as in a vented and closed case environment. In such experiments, the synthetic jet impinges normal to the surface of a packaged thermal test die, comprising a heater and a diode-based temperature sensor. This test assembly allows simultaneous heat generation and temperature sensing of the package, thereby enabling assessment of the performance of the synthetic jet. Using microjet cooling devices, a thermal resistance of 30.1/spl deg/C/W has been achieved (when unforced cooling is used, thermal resistance is 59.6/spl deg/C/W) when the test chip is located at 15mm spacing from the jet exit plane. In order to more directly compare and scale the cooling results, a preliminary study on heat transfer correlations of the microjet cooling device has been performed. Finally, a comparison of the performance of the microjet cooler with standard cooling fans is given.     

A new self-aligned well-isolation technique for CMOS devices

This paper presents the development of a new well-isolation technique for advanced CMOS LSI's. The technique comprises narrow deep trench fabrication utilizing undercut, in addition to silicon-oxide cap formation, which leaves a cavity. The predominant feature of this technique is that well isolation self-aligned to the well region is realized utilizing the trench fabrication technique. Additionally, no crystal defects are observed around the well isolation even after 1000°C annealing following silicon-oxide cap formation. Since the well isolation produced also prevents the latchup phenomenon from occurring due to its depth, this technique enables the CMOS device dimensions to be considerably reduced.     

New technique for measuring the threshold voltage in MOS devices

The present paper describes an experimental method that can be used to measure the threshold voltage in MOS devices in the form of transistors or capacitors. The proposed method is based on the detection of the non-steady-state/steady-state transition of the surface potential at the oxide–semiconductor interface of a MOS device, when it is swept from depletion to inversion regions. This detection is carried out as follows: a set of current versus gate signal frequency measurements, for different voltage amplitudes, is performed. The frequency values corresponding to the maximum measured current (optimum frequency) f_m, are read. Several gate voltage versus optimum frequencies (f_m–V_G) curves are plotted for gate voltage values ranging from 0.2 to 3 V with a 0.1 V step increment. The (f_m–V_G) curves are found to undergo an abrupt change of slope at a specific gate voltage value. The value of threshold voltage is extracted from the critical points of the former curves. Experiments have been carried out on different devices. The measured values of threshold voltage are found to be in good agreement to those obtained by the conventional I_D–V_GS and simulation methods as well as that supplied by the device manufacturer.     

Electrostatic discharge thermal failure in semiconductor devices

The problem of calculating for electrostatic discharge (ESD) thermal failure is considered by the thermal convolution integral technique. It is shown that the common assumption that threshold failure occurs after five time constants is unjustified and that the simple average power method for assessing threshold parameters is, consequently, invalid. New expressions for the threshold parameters are presented which retain the simplicity of the average power method, yet represent only a small sacrifice of the accuracy (typically 5%) of more complex methods. In addition, the relaxation of the constraints of a pure Wunsch-Bell damage profile and of an exponentially decaying current pulse is considered     

A novel fabrication technique for multiple-wavelengthphotonic-integrated devices in InGaAs-InGaAsP laserheterostructures

We report the fabrication of multiple wavelength chips in InGaAs-InGaAsP laser structure using a novel ion implantation induced quantum-well (QW) intermixing technique. This technique first consists of using a gray mask photolithography and reactive ion etching process to create a SiO₂ implant mask with variable thickness on the sample. This is followed by a single 360-keV phosphorus ion implantation at a dose of 1×10¹⁴ cm^-2 at 200°C, which creates different amounts of point defects in the sample depending on the local thickness of the SiO₂ mask. A subsequent thermal annealing step induces QW intermixing through the diffusion of the point defects across the structure. With this technique, we have successfully fabricated 10-channel multiple wavelength laser diodes, with lasing wavelength spreading over 85 nm (between 1.47 and 1.55 μm), monolithically integrated on a single chip. Only a limited increase of threshold current density of 17% (i.e., from 1.2 to 1.4 kA/cm²), has been observed between the least intermixed and the most intermixed lasers     

氦-氖气体激光器的高温玻璃封接技术

1.影响气体激光器寿命的主要因素之一的是反射镜片与激光器管口的真空密封问题.至今国内外已采用光胶、环氧树脂粘合剂胶合封接、低融点玻璃封接和柯伐金属玻璃封接等技术,但都不十分理想.最理想的封接方法是全玻璃直接封接,即把反射镜片的玻璃和激光器管口的玻璃直接融熔封接在一起,但至今未见报道.我们将真空管工艺中高频感应电阻损耗加热方法运用于激光器的制管封接,获得了理想的玻璃直接密封方法.用此方法于1982年制作了一小批氦-氖激光器,效果极好,至今仍在正常工作,激光器的寿命已达5万小时.2.高温玻璃直接密封技术的主要难点是:     

Delay time measurement in transition metal oxide glass devices

The switching delay times for transition metal oxide glass devices vary from operation to operation. However, a statistical treatment of delay time measurements has revealed the voltage dependence of the delay times and the existence of a well-defined threshold voltage for all of the devices tested. The effect of the switch-OFF history on the performance of the devices has also been investigated. Measurements of the transition metal oxide devices are compared with similar work on chalcogenide devices.     

Phosphosilicate glass flow over aluminum in integrated circuit devices

A method of planarizing multilevel metallization struc tures in the fabrication of integrated circuit devices is presented. Radiation from a tunable TEA-CO2laser, under select conditions, is found to flow a layer of phosphosilicate glass, as thin as 1 µm and with as low as 5 % wt phosphorus, over aluminum steps. The flow is accomplished without any evidence of alloying the aluminum to the underlying silicon or melting the aluminum at the glass-to-metal interfaces.