Manufacturing Of Diodes Research Articles

Design and Manufacturing of 1200V SiC JBS Diodes with Low On-State Voltage Drop and Reverse Blocking Leakage Current

This paper presents the design and fabrication of 1200V-rated SiC JBS diodes in a manufacturing environment. Various designs of p+-grids and edge termination structures were proposed and fabricated on 6-inch SiC substrates. Experimental results show that deeper p+ n junctions are necessary to reduce the leakage current in blocking mode of operation. It was also demonstrated that the hybrid-JTE edge termination structure is very efficient to provide a near-ideal breakdown voltage. Ti and Ni Schottky metals were compared with respect to forward voltage drops and reverse blocking behaviors at high temperatures up to 200 °C.

Light-emitting diodes as light sources for spectroscopy: Sensitivity to temperature

Understanding of light-emitting diode lamp behaviour is essential to support the use of these devices as illumination sources in near infrared spectroscopy. Spectral variation in light-emitting diode peak output (680, 700, 720, 735, 760, 780, 850, 880 and 940 nm) was assessed over time from power up and with variation in environmental temperature. Initial light-emitting diode power up to full intensity occurred within a measurement cycle (12 ms), then intensity decreased exponentially over approximately 6 min, a result ascribed to an increase in junction temperature as current is passed through the light-emitting diode. Some light-emitting diodes displayed start-up output characteristics on their first use, indicating the need for a short light-emitting diode ‘burn in’ period, which was less than 24 h in all cases. Increasing the ambient temperature produced a logarithmic decrease in overall intensity of the light-emitting diodes and a linear shift to longer wavelength of the peak emission. This behaviour is consistent with the observed decrease in the IAD Index (absorbance difference between 670 nm and 720 nm, A670–A720) with increased ambient temperature, as measured by an instrument utilising light-emitting diode illumination (DA Meter). Instruments using light-emitting diodes should be designed to avoid or accommodate the effect of temperature. If accommodating temperature, as light-emitting diode manufacturer specifications are broad, characterisation is recommended.

Proton-irradiation technology for high-frequency high-current silicon welding diode manufacturing

Different proton irradiation regimes were tested to provide more than 20 kHz-frequency, soft reverse recovery “snap-less” behavior, low forward voltage drop and leakage current for 50 mm diameter 7 kA/400 V welding diode Al/Si/Mo structure. Silicon diode with such parameters is very suitable for high frequency resistance welding machines of new generation for robotic welding.

Vibration-Assisted Femtosecond Laser Drilling with Controllable Taper Angles for AMOLED Fine Metal Mask Fabrication

This study investigates the effect of focal plane variation using vibration in a femtosecond laser hole drilling process on Invar alloy fabrication quality for the production of fine metal masks (FMMs). FMMs are used in the red, green, blue (RGB) evaporation process in Active Matrix Organic Light-Emitting Diode (AMOLED) manufacturing. The taper angle of the hole is adjusted by attaching the objective lens to a micro-vibrator and continuously changing the focal plane position. Eight laser pulses were used to examine how the hole characteristics vary with the first focal plane’s position, where the first pulse is focused at an initial position and the focal planes of subsequent pulses move downward. The results showed that the hole taper angle can be controlled by varying the amplitude of the continuously operating vibrator during femtosecond laser hole machining. The taper angles were changed between 31.8° and 43.9° by adjusting the vibrator amplitude at a frequency of 100 Hz. Femtosecond laser hole drilling with controllable taper angles is expected to be used in the precision micro-machining of various smart devices.

Experimental Studies of the Frequency Dependence of the Low-Barrier Mott Diode Impedance

We study the microwaave impedance of low-barrier Mott diodes with a $\delta $ -doped layer near the metal contact. Parameters of the elements of the diode equivalent circuit are determined and their dependences on the dc bias voltage are examined. The effects of injection of electrons into the i layer and their time delay in the potential well of the $\delta $ layer under a forward bias are discussed. An original method of the incoming test of epitaxial wafers and the diagnostics of their linear characteristics for the epitaxial structures intended for manufacturing of low-barrier Mott diodes is proposed.

High-Speed Integrated Digital to Light Converter for Short Range Visible Light Communication

Design details and characterization results of an integrated digital to light converter (DLC) for short range visible light communication (VLC) is reported. The integrated DLC can generate 16 light intensity levels at fast switching speeds, up to 500 MHz, thus enabling fast intensity modulated VLC. Data rates up to 365 Mb/s are achieved with bit error rate (BER) $1\times 10^{-3}$ at a link distance of 5 cm and an average electrical power efficiency of 70%. Optimization in the micro light emitting diode ( $\mu $ LED) manufacturing process has resulted in approximately threefold increase in data rate of the system. Spectrally efficient modulation schemes such as orthogonal frequency division multiplexing (OFDM) and pulse amplitude modulation (PAM) are also demonstrated using this integrated system.

High-performance rectifiers fabricated on a flexible substrate

We report on the fabrication and testing of metal-insulator-metal (MIM) diodes on a flexible substrate where the thin insulating layer self-assembles as a monolayer sandwiched between the two metal electrodes. The current-voltage characteristic has a strong asymmetry and non-linearity at zero-bias. The diodes have a typical zero-bias resistance of 80 kΩ, a zero-bias curvature coefficient of 5.5 V−1, and a voltage responsivity of 3.1 kV/W at a frequency of 1 GHz. The fabrication yield was over 90%, and an encapsulation method to prevent MIM junction degradation has also been developed. The diodes show no significant degradation in performance when the substrate is stressed in a one-off bending experiment, although extensive testing does produce some loss in quality. The fabrication process is simple, cost effective, and carried out at low temperature, opening up the possibility of roll-to-roll volume manufacturing of fast MIM diodes.

Sparse Coding-Based Failure Prediction for Prudent Operation of LED Manufacturing Equipment


 
 
 A sudden failure of a critical component in light-emitting diode (LED) manufacturing equipment would result in unscheduled downtime, leading to a possibly significant loss in productivity for the manufacturer. It is therefore important to be able to predict upcoming failures. A major obstacle to failure prediction is the limited amount of equipment lifecycle data available for training, as equipment failure is not expected to be frequent. This calls for machine learning techniques capable of making accurate failure predictions with limited training data. This paper describes such a method based on sparse coding. We demonstrate the prediction performance of the method on a real-world dataset from LED manufacturing equipment. We show that sparse coding can draw out salient features associated with failure cases, and can thus produce accurate failure predictions. We also analyze how sparse coding-based failure prediction can lead to significant efficiency improvements in equipment operation.
 
 

Mixer-Based Characterization of Millimeter-Wave and Terahertz Single-Anode and Antiparallel Schottky Diodes

This paper presents an alternative characterization method to the traditional characterization methods of the millimeter-wave and terahertz Schottky diodes. The diodes can be characterized based on the mixer operation (conversion loss and noise temperature) under comparable conditions. The tuning of the embedding impedances and the easy changing of the diode under test allow the comparison of different diodes in their actual operating environment. A fundamental mixer test jig and a subharmonic mixer test jig are designed for the characterization and comparison of different single-anode and antiparallel Schottky diodes, respectively, at 183 GHz. For the antiparallel diodes, the traditional capacitance extraction is not possible, thus alternative and additional characterization data is valuable. The diode manufacturers can exploit the mixer-based characterization to test the mixer operation of their diode and to reveal possible problems with the diode during the diode development process.

Characterization of a mortar made with cement and sludge from the light-emitting diode manufacturing process

This study uses sludge, which is a by-product of the light-emitting diode (LED) manufacturing process and an industry waste (called LED sludge), to replace some weight percentage of cement. The LED sludge powder was used to replace 5, 10, 20, and 30wt.% of the cement, and the (5×5×5-cm3) sludge-blended cement mortar (SBCM) specimens were molded for a compressive strength test and other engineering property tests. The properties of the LED sludge sample were checked using a scanning electron microscope/energy dispersive X-ray spectrometry (SEM/EDS) analysis, an X-ray diffraction (XRD) analysis, and a solid-state nuclear magnetic resonance spectroscopy (NMR) analysis. The compressive strength test shows that the SBCM specimens have comparable compressive strength relative to ordinary Portland cement mortar (OPCM) specimens in the early curing age of 1–7days, and 103–115% of the compressive strength of OPCM specimens after curing for 14–90days. The test results reveal that the nano-particles promoted the pozzolanic reaction and enhanced the strength evolution. LED sludge can be converted into a useful resource by exempting the difficulty of disposal problems and appealing to the environmental sustainability.

Enhancing mathematical programming models to account for demand priorities increasing as a function of delivery date

Linear and mixed integer programs are frequently used to allocate resources to support a prioritized statement of demands or needs. This paper describes how to enhance these mathematical programming formulations to reflect the dynamic relative importance of demands, namely the priorities of demands – relative to other objectives – increasing as a function of the time of demand fulfillment. We illustrate the modeling using data from a light-emitting diode manufacturer from Taiwan.

Получение двухсторонних высоковольтных эпитак­сиальных кремниевых p—i—n-структур методом ЖФЭ

Silicon p—i—n-structures are usually obtained using conventional diffusion method or liquid phase epitaxy (LPE). In both cases, the formation of p- and n-layers occurs in two stages. This technological approach is quite complex. Moreover, when forming bilateral high-voltage epitaxial layers, their parameters significantly deteriorate as a result of prolonged heat treatment of active high-resistivity layer. Besides, when using diffusion method, it is impossible to provide good reproducibility of the process. In this paper a technique of growing bilateral high-voltage silicon p—i—n-structures by LPE in a single process is proposed. The authors have obtained the optimum compounds of silicon-undersaturated molten solutions for highly doped (5•1018 cm–3) contact layers: 0.4—0.8 at. % aluminum in gallium melt for growing p-Si-layers and 0.03—0.15 at. % ytterbium in tin melt for n-Si-layers. Parameters of such structures provide for manufacturing of high-voltage diodes on their basis. Such diodes can be used in navigational equipment, communication systems for household and special purposes, on-board power supply systems, radar systems, medical equipment, etc.

Defect specific photoconductance: Carrier recombination through surface and other extended crystal imperfections

The analysis of carrier recombination through defects using a unified approach, common to all extended defects independent of their dimensionality is presented. The considered crystal defects include surface, grain boundaries, dislocations, and clusters of crystal defects and impurities. It is shown that, at low carrier injection levels, carrier recombination through extended defects is controlled by the electrostatic potential barrier formed at the defects. The barrier model is applied to the analysis of the photoconductance in the defect controlled regions. Unlike in the case of recombination through point defects in the bulk, which is characterized by the linear dependence of the steady-state photoconductance on the light intensity and exponential decay of the photoconductance after cessation of the illumination, the photoconductance associated with recombination through extended defects under depletion conditions exhibits logarithmic dependence on the light intensity and characteristic logarithmic decay after cessation of the illumination. The predictions of the “barrier-controlled recombination” model are compared with the measurements of photoconductance in electronic grade silicon. Differentiation between time dependences of the photoconductance decay associated with recombination through the point defects and through the extended crystal imperfections is used as a basis of the defect specific photoconductance (DSPC) methodology. It is shown that DSPC allows for the separation of the bulk and surface characteristics without any additional surface treatments, enabling electrical characterization of both bulk and thin-film wafer structures critical for photovoltaic (PV) solar cell and high-brightness light emitting diode (HB-LED) manufacturing. The comparison of the “barrier-controlled recombination” and standard diffusion model based on surface recombination velocity is discussed.

Outsourcing evaluation system based on AHP/ANP approach for LED industry

Besting coordinate buyer and supplier efforts to improve productivity and competitive advantage in a supply chain is an important issue. Many studies have proposed models, principles, and criteria to evaluate and select the supplier. This study proposes a measurement model for generating performance indicators and evaluating supplier performance in order to help managers to realize the advantages and disadvantages of suppliers. The analytical hierarchy process (AHP) and the analytical network process (ANP) are utilized to determine the weight of each criterion when generating the performance model. Finally, this study uses a data sample of an light emitting diode (LED) manufacturer in Taiwan and company’s three main suppliers to test the evaluation model.

Narrow linewidth laterally-coupled 1.55 µm DFB lasers fabricated using nanoimprint lithography

A report is presented on the use of nanoimprint lithography for the fabrication of InP-based laterally-coupled ridge waveguide distributed feedback laser (DFB) diodes emitting around 1550 nm. At room temperature the uncoated lasers exhibited a sidemode suppression ratio of 50 dB at an output power of 6 mW. The lasers showed extremely pure singlemode spectrum with the Lorentzian part of the measured linewidth being ∼200 kHz. The results prove that nanoimprint lithography is suitable for the low-cost manufacturing of high performance singlemode laser diodes.

Improving supplier performance using a comprehensive scheme

Improving and coordinating buyer and supplier efforts to increase productivity and competitive advantage in a supply chain is an important issue. Numerous studies have proposed models, principles and criteria for supplier evaluation and selection. Hence, evaluating and improving supplier performance are important when building long-term supply chain competitiveness. This study presents a novel and comprehensive framework that illustrates the linkages between evaluating supplier performance and planning improvements. The proposed framework comprises four parts: building an evaluation model, evaluating supplier performance based on the buyer perspective, evaluating supplier performance based on the supplier perspective and scheduling improvement tasks. This study applies a hybrid genetic algorithm to help suppliers schedule improvement tasks based on the evaluation findings. Finally, evaluation data of a light-emitting diode (LED) manufacturer in Taiwan is used to interpret the procedure and verify model effectiveness.

Sublimation Point Depression of Small-Molecule Semiconductors by Sonocrystallization

Small-molecule semiconductor solids such as pentacene and tris(8-hydroxyquinoline)aluminum(III) (Alq3) were dispersed in a poor solvent, like water, and insonated in a 10 mL scintillation vial with an output frequency of 20 kHz, a voltage of 1500 V, and an optimal induction time for 10 min at −13 °C. Sonocrystallization, at a low bulk solution temperature, gave pentacene powders of a high lattice energy difference value, ΔElatt, of 2.258 J/g (i.e., 0.6285 kcal/mol) caused by the poor crystallinity of 69% and produced Alq3 powders with only 37 wt % of the stable α-form and 63 wt % of the metastable ε-form mixed with an amorphous phase. Therefore, insonated pentacene and Alq3 powders had depressed sublimation points of 210 and 180 °C, respectively. However, surface energy and impurities had nothing to do with the sublimation point depression. The sublimation point depression of target materials could reduce the heating and cooling duty of the vapor-phase deposition method for the manufacturing of organic light-emitting diodes (OLEDs), organic thin-film transistors (OTFTs), and photovoltaic (PV) cells drastically, because the total radiant-heat-transfer rate between heated surfaces is proportional to the fourth power of the absolute temperature according to the Stefan−Boltzmann law.

Patterned Organic and Inorganic Composites for Electronic Applications

Carbon nanotube (CNT) and polymer composite materials were obtained using two manufacturing processes. The first method is dispersion of CNT in a solvent-doped poly(ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) solution. The composite retains high optical properties because of the polymeric system and shows improved electrical properties. The second method is in situ polymerization of ethylenedioxythiophene (EDOT) in the presence of CNT. This procedure assures a uniform CNT distribution in a highly conductive p-EDOT layer with reduced optical transmittance. The composites were analyzed for optical transmittance, surface energy, polarity, distribution, and resistivity, and then they were used as an anodic layer in organic light-emitting diode (OLED) manufacturing. The device performances were characterized and compared to that of conventional devices with an indium tin oxide anode. p-EDOT composite layers have shown conductivity and optical transmittance suitable to produce an OLED with a 10 cd/A efficiency.

Manufacturing of laser diodes grown by molecular beam epitaxy for coarse wavelength division multiplexing systems

Molecular beam epitaxy (MBE) was used to grow ridge-waveguide distributed feedback (DFB) lasers for uncooled coarse wavelength division multiplexing applications. The lasers covered a wavelength range from 1270to1610nm and a temperature range of at least −20to85°C. The MBE growth includes atomic hydrogen cleaning of exposed InGaAsP surfaces for regrowth over a DFB grating. The devices show good performance over the whole wavelength range, with 85°C median threshold currents from 25to40mA depending on the wavelength. Accelerated lifetime testing indicates minimal degradation with TO packaged devices showing less than a 1% increase in operating current after 4000h at 85°C.

A case-based decision support system for product development

Companies that are developing new products are now facing increasing global competition. Continual success in the marketplace depends upon how efficiently and effectively a company is able to respond to customers' ever changing needs. In this article, a Case-based Product-development Enhancement System (CPES) is designed to help manufacturing industry to support product development by retrieving and analysing useful knowledge and solutions in a timely and cost-effective manner. CPES provides important support for, and information on product development, and enhances effectiveness in product development strategies by integrating techniques such as data warehouse, Online Analytical Processing and Case-Based Reasoning. When applying CPES in a light emitting diode manufacturer, it was possible to maximise resource utilisation, increase work efficiency and greatly reduce cost in product development.