Reliability of Active-Matrix Organic Light-Emitting-Diode Arrays With Amorphous Silicon Thin-Film Transistor Backplanes on Clear Plastic

We have fabricated active-matrix organic light emitting diode (AMOLED) test arrays on an optically clear high-temperature flexible plastic substrate at process temperatures as high as 285 degC using amorphous silicon thin-film transistors (a-Si TFTs). The substrate transparency allows for the operation of AMOLED pixels as bottom-emission devices, and the improved stability of the a-Si TFTs processed at higher temperatures significantly improves the reliability of the light emission over time.     

Amorphous Silicon Thin-Film Transistor Backplanes Deposited at 200 °C on Clear Plastic for Lamination to Electrophoretic Displays

The transition of thin-film transistor (TFT) backplanes from rigid plate glass to flexible substrates requires the development of a generic TFT backplane technology on a clear plastic substrate. To be sufficiently stable under bias stress, amorphous-silicon (a-Si:H) TFTs must be deposited at elevated temperatures, therefore the substrate must withstand high temperatures. We fabricated a-Si:H TFT backplanes on a clear plastic substrate at 200degC. The measured stability of the TFTs under gate bias stress was superior to TFTs fabricated at 150degC. The substrate was dimensionally stable within the measurement resolution of 1, allowing for well-aligned 8 times 8 and 32 times 32 arrays of pixels. The operation of the backplane is demonstrated with an electrophoretic display. This result is a step toward the drop-in replacement of glass substrates by plastic foil.     

Solid-phase Crystallization of Hydrogenated Amorphous Silicon on Glass Substrates

Amorphous silicon films prepared by PECVD on glass substrate have been crystallized by conventional furnace annealing and rapid thermal annealing（RTA）, respectively. From the Raman spectra, X- ray diffraction and scanning electron microscope, it is found that the grain size is crystallized at 850 ℃ in both techniques. The thin film made by RTA is smooth and of perfect structure, the thin film annealed by FA has a highly structural disorder. An average grain size of about 30 nm is obtained by both techniques.     

Comparison of Pentacene and Amorphous Silicon AMOLED Display Driver Circuits

Organic light-emitting diode (OLED) displays offer distinct advantages over liquid crystal displays for portable electronics applications, including light weight, high brightness, low power consumption, wide viewing angle, and low processing costs. They also are attractive candidates for highly flexible substrates. In active-matrix OLED (AMOLED) displays, a small transistor circuit is used to drive each OLED device. This paper compares the simulated performance of two state-of-the-art AMOLED drivers with a proposed 5 thin-film-transistor (TFT) voltage programmed driver circuit which combines the advantages of the first two configurations. A competitive evaluation is also done between amorphous silicon (alpha-Si) and organic TFTs (OTFTs,) using comparable empirical device models for alpha-Si) and pentacene OTFTs. The 5-TFT circuit is found to match the speed of the 2-TFT while achieving a stability closer to the 4-TFT circuits and demonstrating a better speed-stability tradeoff.     

激光脉冲频率对不同衬底上非晶硅薄膜晶化的影响

应用不同频率的YAG激光分别对单晶硅及多晶硅衬底上的非晶硅薄膜进行了退火处理。晶化后的非晶硅薄膜的物相结构和表面形貌用XRD和AFM进行分析。XRD测试结果表明:随着激光频率的增加,两种衬底上的非晶硅薄膜晶化晶粒尺寸均出现了先增加后降低的现象。所有非晶硅样品的衍射峰位与衬底一致,说明非晶硅薄膜的晶粒生长是外延生长。从多晶硅衬底样品的XRD可以看出,随着激光频率的增加,激光首先融化衬底表面,然后衬底表层与非晶硅薄膜一起晶化。非晶硅薄膜最佳晶化激光频率分别为:多晶硅衬底20Hz,单晶硅衬底10Hz。     

硅衬底微波集成电路

硅衬底微波集成电路具有诱人的发展前景。本文阐述了硅材料用作微波集成电路衬底的优点,分析了硅衬底微波传输线、无源元件以及锗硅异质结双极晶体管（SiGeHBT)的电性能,介绍了目前国外硅衬底微波集成电路研究的进展,并对数字电路与RF及微波电路在硅衬底上混合集成的特点与应用作了讨论。     

Low-Temperature Epitaxy of Compressively Strained Silicon Directly on Silicon Substrates

We report epitaxial growth of compressively strained silicon directly on (100) silicon substrates by plasma-enhanced chemical vapor deposition. The silicon epitaxy was performed in a silane and hydrogen gas mixture at temperatures as low as 150°C. We investigate the effect of hydrogen dilution during the silicon epitaxy on the strain level by high-resolution x-ray diffraction. Additionally, triple-axis x-ray reciprocal-space mapping of the samples indicates that (i) the epitaxial layers are fully strained and (ii) the strain is graded. Secondary-ion mass spectrometry depth profiling reveals the correlation between the strain gradient and the hydrogen concentration profile within the epitaxial layers. Furthermore, heavily phosphorus-doped layers with an electrically active doping concentration of ~2 × 10²⁰ cm⁻³ were obtained at such low growth temperatures.     

Complementary Logic Gates and Ring Oscillators on Plastic Substrates by Use of Printed Ribbons of Single-Crystalline Silicon

CMOS inverters and three-stage ring oscillators were formed on flexible plastic substrates by transfer printing of p-type and n-type single crystalline ribbons of silicon. The gain and the sum of high and low noise margins of the inverters were as high as ~150 and 4.5 V at supply voltages of 5 V, respectively. The frequencies of the ring oscillators reached 2.6 MHz at supply voltages of 10 V. These results, as obtained with devices that have relatively large critical dimensions (i.e., channel lengths in the several micrometer range), taken together with good mechanical bendability, suggest promise for the use of this type of technology for flexible electronic systems.     

Si衬底氮化物LED器件的研究进展

通过对比分析目前氮化物LED的三种主要衬底即蓝宝石、SiC与Si的技术特点,指出了发展Si衬底LED的重要意义。详细介绍了目前国内外Si衬底LED的研究现状,解析了在Si衬底上制备LED的多种新型技术,主要包括以提高薄膜沉积质量为目的的缓冲层技术、激光脱离技术、图案掩模技术、阳极氧化铝技术,以及以提高光提取率为宗旨的镜面结构技术和量子阱/量子点技术。这些新型技术与传统的MOCVD,HVPE,MBE等制备技术相结合,在很大程度上克服了Si衬底的不足,使Si衬底上氮化物LED展现出广阔的发展前景。     

Aligned Growth of Semiconductor Nanowires on Scratched Amorphous Substrates

Aligned growth of planar semiconductor nanowires (NWs) on crystalline substrates has been widely demonstrated during the past two decades and was used for the fabrication of a large variety of devices. However, the dependence on single-crystal substrates is a major obstacle in the way of implementing NW-based applications in today's silicon- and glass-based technologies. Here, the guided growth of semiconductor NWs is demonstrated along nanoscale-depth scratches, created in a nonlithographic process on amorphous oxidized silicon wafers and soda-lime glass. Scratches are created on the substrates in a few seconds using a robust and scalable mechanical polishing process. Growth of planar NWs of different materials (CdS, CdSe, ZnSe, and ZnO) guided by scratches on Si/SiO₂ wafers and glass is demonstrated and studied. Photoluminescence measurements from individual NWs grown along scratches show that the interaction with the substrate preserves the optical properties of the material. Crystallographic analysis indicates that all materials grow as single crystals, and the influence of the scratches on the different materials is discussed in terms of morphology, crystallinity, and crystallographic orientations. This process opens the way to large-scale integration of NWs into functional devices by guided growth for various applications including displays, polarized light sensors, and smart windows.     

Self-Stabilization in Amorphous Silicon Circuits

Thin-film transistors (TFTs) based on disordered semiconductors such as amorphous hydrogenated silicon (a-Si:H) experience a threshold voltage (VT) shift with time in the presence of a gate bias. The VT shift needs to be compensated for circuit applications. We study an interesting property of self-compensation in fundamental analog TFT circuits with one a part of the circuit compensating for the effects of VT shift in the other and vice versa.      

High-Rate Deposition of Amorphous Silicon

A method for rapid deposition of amorphous silicon (a-Si) films in a low-frequency (55 kHz) glow discharge plasma is suggested. The structure and electrophysical properties of the films were investigated. It is shown that the use of the low-frequency discharge makes it possible to independently control the stability and concentration of recombination centers in a-Si. This fact, along with the possibility of fabricating heterostructures with a low density of surface states, makes this method promising for mass production of a-Si-based electron devices.     

非晶硅液晶光阀投影系统

首次介绍一种以非晶硅（ａ－Ｓｉ）为光导层的ＬＣＬＶ投影系统，该系统具有响应速度快、写入光谱范围宽及工艺简单等优点。分析了ＬＣＬＶ驱动信号的电压幅值、频率、占空比以及屏幕照度等诸多因素对投影系统对比度特性的影响。该投影系统屏幕尺寸为１．５ｍ×１．２ｍ，最大照度为１９０ｌｘ，分辨率优于２０ｌｐ／ｍｍ，响应时间小于１ｍｓ。可完成实时动态图像投影。     

Sensing Amorphous/Crystalline Silicon Surface Passivation by Attenuated Total Reflection Infrared Spectroscopy of Amorphous Silicon on Glass

Semiconductors - Attenuated total reflection Fourier transform infrared (ATR FTIR) spectroscopy and effective lifetime measurements have been used to characterize amorphous/crystalline silicon...     

硅基键合激光器的研究进展

硅基的光电子集成以及光集成将满足未来信息传输处理的要求。目前制作硅基激光器的方法主要分为两类,异质结外延生长和异质材料键合。键事方法克服了异质结外 可避免的晶格失配和材料热膨胀系数非共容性的缺点,它可以将具有直接带隙结构的半导体材料键合到硅片上,从而制作出硅基键合激光器件。特别是年来来发展起来的低落曙直接合技术,使发光器件与微电子器件的硅基混合光电集成成为可能。     

非晶硅和非晶硅锗薄膜的金属诱导结晶

分析了金属Ni、Al诱导非晶Si及非晶SiGe薄膜结晶的条件、特点和机理.简要介绍了金属诱导结晶相对于其它一些结晶工艺的优势及其在薄膜晶体管中的应用.概述了影响诱导结晶速率和薄膜微结构的诸多因素,如热处理条件和外加电场等.对电场增强金属诱导横向结晶的相关问题进行了探讨,指出适当强度的电场可显著加快横向诱导结晶的速率,但更强电场则会降低该速率,基于电迁移效应对该现象进行了解释.     

Micromachined Loop Antennas on Low Resistivity Silicon Substrates

The integration of K-band (20-40 GHz) full wavelength square wire- and slot-loop antennas on low resistivity (11-70 Omegacm) silicon substrates is addressed. By the use of polymer or silicon oxide/nitride membranes to support the slot or wire loop over micromachined trenches the efficiency of the antennas is enhanced while the majority of the bulk silicon within the aperture of the antenna is preserved to enable the integration of active devices. A 3.6times3.6 mm² large slot loop antenna chip with 200 mum micromachined trench width yields 1.5 dBi gain at 29.5 GHz, while 1.0 dBi gain is obtained at 24 GHz for a wire loop antenna on a 4.5times4.5 mm² large chip with 360 mum wide trenches     

Resonant-Cavity-Enhanced Single-Photon Avalanche Diodes on Reflecting Silicon Substrates

In this letter, we report the first resonant-cavity-enhanced single-photon avalanche diode (RCE SPAD) fabricated on a reflecting silicon-on-insulator (SOI) substrate. The substrate incorporates a two-period distributed Bragg reflector fabricated using a commercially available double-SOI process. The RCE SPAD detectors have peak photon detection efficiencies ranging from 42% at 780 nm to 34% at 850 nm and time resolution of 35-ps full-width at half-maximum. Typical dark count rates of 450, 3500, and 100 000 c/s were measured at room temperature with RCE SPADs having, respectively 8-, 20-, and 50-mum diameter.     

Realization of Flexible Plasma Display Panels on PET Substrates

DC plasma display panels are fabricated on flexible polyethylene terephtalate (PET) substrates. Each pixel consists of laterally placed anode and cathode electrodes. All electrical elements are formed on a single PET substrate, whereas a second substrate is needed to encapsulate the panel. Silver is used as the metal for each electrode and standard photolithography is used to form each cell. A 150-/spl mu/m-thick layer of a UV-curable polymeric adhesive was used to form barrier ribs to both electrically isolate neighboring cells and to encapsulate the plasma. Conversion of vacuum UV into visible light is possible by blast-embedding of proper phosphor grains into the top substrate. The current-voltage and turn-on voltage versus pressure characteristics are examined. Effect of curvature on turn-on voltage is addressed.     

NIP型非晶硅薄膜太阳能电池的研究

采用射频等离子体增强化学气相沉积(RF-PECVD)技术制备非晶硅(a-Si)NIP太阳能电池,其中电池的窗口层采用P型晶化硅薄膜,电池结构为Al/glass/SnO2/N(a-Si:H)/I(a-Si:H)/P(cryst-Si:H)/ITO/Al.为了使P型晶化硅薄膜能够在a-Si表面成功生长,电池制备过程中采用了H等离子体处理a-Si表面的方法.通过调节电池P层和N层厚度和H等离子体处理a-Si表面的时间,优化了太阳能电池的制备工艺.结果表明,使用H等离子体处理a-Si表面5 min,可以在a-Si表面获得高电导率的P型晶化硅薄膜,并且这种结构可以应用到电池上;当P型晶化硅层沉积时间12.5 min,N层沉积12 min,此种结构电池特性最好,效率达6.40%.通过调整P型晶化硅薄膜的结构特征,将能进一步改善电池的性能.