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Instruments Today, No. 166 (vol. 30, issue 2)

October 2008 published

Nano Device Technology

6

LEDs Lighting Options and Design Considerations
Yu-Lung Tung, Chung-Hao Tien

LEDs make a rapid progress during the last few years since Nichia Co. successfully delivered the high power blue and white LED chips in 1996. After that, LED-based luminaries become a promising approach for future lighting applications. Unlike the conventional incandescent or fluorescent sources, LEDs have relatively narrow spectral power distribution, which leads to some unique characteristics and needs to be considered in lighting criterion. This article is aimed to briefly introduce the LED-based lighting options and design considerations in many aspects such as color rendering, luminous efficiency and color temperature.

14

High Efficiency GaAs Solar Cells Using Indium-Tin-Oxide Nano-Columns
Chia-Hua Chang, Min-Hsiang Hsu, Chin-Sheng Yang, Min-An Tsai, Peichen Yu, Chin-Hua Chiu, Hao-Chung Kuo

An array of conductive indium-tin-oxide (ITO) nano-columns is deposited on GaAs solar cells using the glancing angle deposition (GLAD) method. Calculations based on a rigorous coupled-wave analysis method show that such ITO nano-columns offer superior angular and spectral anti-reflective (AR) properties. The optical characteristics of the ITO nano-columns are described. The conversion efficiency of GaAs solar cells with ITO nano-columns as the AR coating is increased by 23%.

21

Novel Sol-Gel Derived Nonvolatile Nanocrystal Memory Devices
Yi-Jen Tsai, Chi-Chang Wu, Pin-Lin Liu, Fu-Hsiang Ko

In this study, the formation mechanism of nanocrystals (NCs) from the sol-gel spin-coating method had been studied. The ZrCl₄, HfCl₄, and SiCl₄ were used as the sol-gel precursors to form the hafnium and zirconium silicate after rapid thermal annealing at high temperature. We evaluated the impact of temperature and preparation solvent type for the formation of sol-gel derived nanocrystals. In addition, the performance of flash memory with the nanocrystal as the charge trapping layer was also demonstrated.

28

Development of Novel Micro Tensile Testing Instruments and Application in Characterizing Thin Films Mechanical Properties
Yung-Dong Lau, Tso-Chi Chang, Weileun Fang

The mechanical properties of thin film is very important information to design and apply MEMS devices. Tensile testing can extract the mechanical properties by simply mechanical behavior. There are even more on-going researches involving in the mechanical properties testing related fields. In the article, the authors research group in the Micro-Device Lab., National Tsing Hua University would like to introduce the design and fabrication of the tensile testing instrument. It's not easy to integrate the test specimen with the testing instrument due to etch selectivity. This research will provide a brand-new concept, using parylene passivation technique to protect the test specimen during etching processes. Parylene is a very inert chemically to the various etching test. The parylene passivation technique allows the user to change the test sample easily using the same fabrication process. Furthermore, the problems and difficulties resulting from the alignment and assembly of a thin film test specimen with the testing instrument can be prevented. The MEMS instrument consists of a thermal actuator, differential capacitance sensor, and supporting spring. Moreover, the load and displacement relationship can be calibrated by commercial instruments. In application, this study can be determining the mechanical properties.

42

Deep Trench Technology for CMOS CPW and On-Chip Isolation
Shey-Shi Lu, Tao Wang

A coplanar waveguide (CPW) was implemented in 0.13 µm CMOS technology and then post-processed by CMOS compatible inductively-coupled plasma (ICP) etching, which removes the silicon underneath the coplanar strips. Transmission line parameters such as characteristic impedance Z₀, attenuation constant, substrate capacitance/conductance C/G, series inductance/resistance L/R, as a function of frequency were extracted. It is found that a, C and G are greatly improved after silicon removal. At 20 GHz, α is decreased from 0.5 dB/mm to 0.05 dB/mm, G is reduced from 1.6 mS/mm to ~ 0 mS/mm and C is lowered by 56%. The experiment shows that deep trench technology is capable to promote the performance of coplanar waveguide profoundly. Besides the CPW, the technique was further used for on-chip isolation purpose, aimed to solve the problem of substrate leakage. The result shows an extra 32 dB isolation at 2 GHz was contributed by this technique. From these experiments, it is evidenced that deep trench technology should be promising in CMOS MMIC and SOC applications.

48

TEM 3D Imaging Techniques
Jong-Shing Bow

Besides high resolution for 2D images, TEM also offers 3D imaging ability which is able to explore 3D microstructure in the materials. TEM stereo microscopy can resolve simple crystal defect structure such as dislocations, stacking faults, and some precipitates with defined crystal planes; while TEM tomography is a more complicated technique, which including acquisition, alignment, reconstruction, and visualization for steps, being applied to explore more complicated microstructure including the architectures of semiconductor devices.

55

Application of Atomic Layer Deposition on Template-Directed Growth of Nanostructures
Chi-Chung Kei, Chih-Chieh Yu, Wen-Hao Cho, Chien-Nan Hsiao

Atomic layer deposition (ALD) is widely applied in semiconductor industry due to excellent film thickness control, step coverage and large-area uniformity. Recently, more and more efforts have been put on the applications of ALD on preparation or surface modification of nanostructures. In this article, the concept of ALD will be given first, followed by the preparations of nanostructures by using ALD with different templates. Applications of ALD on field emitter, photonic crystal device and solar cell are also elucidated.

65

Numerical Simulation of Lightweighted Mirror in Remote Sensing Instruments
Yu-Chuan Lin, Long-Jeng Lee

The primary mirror is one of the critical components of telescope to get high-quality images. Lightweight design and numerical analysis of mirrors are very important issues for weight reduction and performance optimization of satellite payload. This article reports the design process and numerical simulation of lightweight mirror, which consists of the regular geometry, natural frequency and deformation derived from various acceleration values. The numerical result shows that the lightweighted mirror geometry is gained by this approach.

79

Dry Vacuum Pump Technology Application Experiences in Solar Market
Arthur Lin

There are two main technologies applied on the solar cell manufacturing process; one is thin-film based while the other is wafer based. The process can be divided into three phases: preparation of base materials, production of solar cells, and lamination of solar module. In these three phases vacuum technology plays a critical role. In this article, we will elaborate on the challenges regarding the production of solar module in these three phases and their possible solutions at present.

87

The Technology and Development Trend of Integrated Optical Film for Flat Panel Display
Hui-Hsiung Lin, Yu-Nan Pao, Chia-Wei Yu

The optical film of the backlight module of the liquid crystal display provides the optical characteristics on improving luminance, increasing homogeneity, and reducing moiré. In recent years, there are significant changes on optical films, specifically on diffuser film, prism film, polarized bright enhance film, and light guide plate. It has become a new model optical film with compound utilities. This integrated model has replaced the old single film models in reducing the amount of films to be used, thus substantially reduces the cost. This article probes into the edgy technologies and trend through an analysis on relevant patents and techniques and the manufacturing techniques from a worldwide angle.