An integrated optical receiver in MS/RF CMOS process

A monolithically integrated optoelectronic receiver was realized utilizing a deep sub-micron MS/RF CMOS process. Novel photo-diode with STI and highspeed receiver circuit were designed. This OEIC takes advantage of several new features to improve the performance.

A 5GHz low power WLAN transceiver SiGe RFIC for personal communication terminal applications

A low-cost low-power single chip WLAN 802.11a transceiver is designed for personal communication terminal and local multimedia data transmission. It has less than 130mA current dissipation, maximal 67dB gain and can be programmed to be 20dB minimal gain. The receiver system noise figure is 6.4dB in hige-gain mode.

A wide-band front-end for terrestrial and cable receptions

In this paper, a wide-band low noise amplifier, two mixers and a VCO with its buffers implemented in 50GHz 0.35 mu m SiGe BiCMOS technology for dual-conversion digital TV tuner front-end is presented. The LNA and up-converting mixer utilizes current injection technology to achieve high linearity. Without using inductors, the LNA achieves 0.1-1GHz wide bandwidth and 18.8-dB gain with less than 1.4-dB gain variation. The noise figure of the LNA is less than 5dB and its 1dB compression point is -2 dBm. The IIP3 of two mixers is 25-dBm. The measurement results show that the VCO has -127.27-dBc/Hz phase noise at 1-MHz offset and a linear gain of 32.4-MHz/V between 990-MHz and 1.14-GHz. The whole chip consume 253mW power with 5-V supply.

High efficiency RFID UHF power converter

The paper proposes a high efficiency RFID UHF power converter unit to overcome the low efficiency problem. This power converter is mainly composed of an RF-DC converter and a DC-DC converter. In order to overcome the low efficiency problem in low current consuming condition, a DC-DC converter is added to conventional single RF-DC converter rectifier to increase the rectifying efficiency of the RFDC rectifier. The power converter is implemented in a 0.18 um mixed signal, 1p6m CMOS technology. Simulation shows the power converter has an average improvement of 5% and can achieve efficiency as high as 30% with 900MHz, 16uW RF input power and 1.3 V 3.6uA DC output.

Hydrogenated p-type nanocrystalline silicon in amorphous silicon solar cells

A wide bandgap and highly conductive p-type hydrogenated nanocrystalline silicon (nc-Si:H) window layer was prepared with a conventional RF-PECVD system under large H dilution condition, moderate power density, high pressure and low substrate temperature. The optoelectrical and structural properties of this novel material have been investigated by Raman and UV-VIS transmission spectroscopy measurements indicating that these films are composed of nanocrystallites embedded in amorphous SiHx matrix and with a widened bandgap. The observed downshift of the optical phonon Raman spectra (514.4 cm(-1)) from crystalline Si peak (521 cm(-1)) and the widening of the bandgap indicate a quantum confinement effect from the Si nanocrystallites. By using this kind of p-layer, a-Si:H solar cells on bare stainless steel foil in nip sequence have been successfully prepared with a V c of 0.90 V, a fill factor of 0.70 and an efficiency of 9.0%, respectively. (c) 2006 Elsevier B.V. All rights reserved.

Heterojunction solar cells with n-type nanocrystalline silicon emitters on p-type c-Si wafers

Hydrogenated nanocrystalline silicon (nc-Si:H) n-layers have been used to prepare heterojunction solar cells on flat p-type crystalline silicon (c-Si) wafers. The nc-Si:H n-layers were deposited by radio-frequency (RF) plasma enhanced chemical vapor deposition (PECVD), and characterized using Raman spectroscopy, optical transmittance and activation energy of dark-conductivity. The nc-Si:H n-layers obtained comprise fine grained nanocrystallites embedded in amorphous matrix, which have a wider bandgap and a smaller activation energy. Heterojunction solar cells incorporated with the nc-Si n-layer were fabricated using configuration of Ag (100 nm)/1T0 (80 nm)/n-nc-Si:H (15 nm)/buffer a-Si:H/p-c-Si (300 mu m)/Al (200 nm), where a very thin intrinsic a-Si:H buffer layer was used to passivate the p-c-Si surface, followed by a hydrogen plasma treatment prior to the deposition of the thin nanocrystalline layer. The results show that heterojunction solar cells subjected to these surface treatments exhibit a remarkable increase in the efficiency, up to 14.1% on an area of 2.43 cm(2). (c) 2006 Elsevier B.V. All rights reserved.

Hydride Vapor Phase Epitaxy Growth of Semipolar, 10(1)over-bar(3)over-barGaN on Patterned m-Plane Sapphire

We have investigated the hydride vapor-phase epitaxy growth of (10 (1) over bar(3) over bar)-oriented GaN thick films on patterned sapphire substrates (PSSs) (10 (1) over bar0). From characterization by atomic force microscopy, scanning electron microscopy, double-crystal X-ray diffraction, and photoluminescence (PL), it is determined that the crystalline and optical qualities of (10 (1) over bar(3) over bar) GaN epilayers grown on the cylindrical PSS are better than those on the flat sapphire. However, two main crystalline orientations (10 (1) over bar(3) over bar) and (11 (2) over bar2) dominate the GaN epilayers grown on the pyramidal PSS, demonstrating poor quality. After etching in the mixed acids, these (10 (1) over bar(3) over bar) GaN films are dotted with oblique pyramids, concurrently lining along the < 30 (3) over bar2 > direction, indicative of a typical N-polarity characteristic. Defect-related optical transitions of the (10 (1) over bar(3) over bar) GaN epilayers are identified and detailedly discussed in virtue of the temperature-dependent PL. In particular, an anomalous blueshift-redshift transition appears with an increase in temperature for the broad blue luminescence due to the thermal activation of the shallow level.

Monolithic optical gates based on integration of evanescently-coupled uni-traveling-carrier photodiodes and electroabsorption modulators

We report on chip-scale optical gates based on the integration of evanescent waveguide unitraveling-carrier photodiodes (EC-UTC-PDs) and intra-step quantum well electroabsorption modulators (IQW-EAMs) on n-InP substrates. These devices exhibit simultaneously 2.1 GHz and -16.2 dB RF-gain at 21 GHz with a 450 Omega thin-film resistor and a bypass capacitor integrated on a chip.

Tunable Ag surface-plasmon-resonance wavelength and its application on the photochromic behavior of TiO2-Ag films

Surface and bulk plasmon resonance of noble metal particles play an essential role in the multicolor photochromism of semiconductor systems containing noble metal particles, Here we examined several key parameters affecting surface plasmon resonance wavelength (SPRW) of Ag particles and investigated the relation between surface plasmon and photochromic reaction wavelength. From the transmission spectra of sandwiched (TiO2/Ag/TiO2) and overcoated (Ag/TiO2) films deposited on quartz substrates at room temperature by rf helicon magnetron sputtering, we demonstrated that the SPRW can be made tunable by changing the surrounding media and thickness of the metal layer. The coloration and bleaching in visible light region due to photochromism were clearly observed for the films inserted with a 0.55 nm Ag layer.

ZnO thin film photoconductive ultraviolet detector with fast photoresponse

C-axis preferred oriented ZnO thin films were prepared on quartz substrates by RF sputtering. Photoconductive ultraviolet detector with planar interdigital electrodes was fabricated on ZnO thin film by the lift off technique. Linear I-V characteristic was observed under dark or 365 nm UV light illumination and has obvious difference. The photoresponsivity of 365 nm at 5 V bias is 18 A/W. The response time measure set mainly contains KrF excimer laser with the pulse width of 30 ns and the oscillograph with the bandwidth of 200 MHz. The result shows fast photoresponse with a rise time of 100 ns and fall time of 1.5 mu s. (c) 2005 Elsevier B.V. All rights reserved.

SOA-based actively mode-locked fiber ring laser by forward injecting an external pulse train

An actively mode-locked fiber ring laser based on cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA) is demonstrated to operate stably with a simple configuration. By forward injecting an easily-generated external pulse train, the mode-locked fiber laser can generate an optical-pulse sequence with pulsewidth about 6 ps and average output power about 7.9 mW. The output pulses show an ultra-low RMS jitter about 70.7 fs measured by a RF spectrum analyzer. The use of the proposed forward-injection configuration can realize the repetition-rate tunability from I to 15 GHz for the generated optical-pulse sequences. By employing a wavelength-tunable optical band-pass filter in the laser cavity, the operation wavelength of the designed SOA-based actively mode-locked fiber laser can be tuned continuously in a wide span between 1528 and 1565 nm. The parameters of external-injection optical pulses are studied experimentally to optimize the mode-locked fiber laser. (C) 2009 Elsevier B.V. All rights reserved.

石英晶体微天平在电极表面反应研究中的应用

石英晶体微天平（QCM）具有高灵敏度检测质量变化的特点，在电化学、分析化学以及生物化学等研究领域都有广泛的应用。特别是电化学石英晶体微天平体（EQCM），已经成为电化学研究的一种有力手段。本人在工作期间应用QCM/EQCM进行了如下研究：首次提出了云母作为QCM石英晶振新型表面材料的设想，并成功地制成云母-石英晶振子，其在气相、液相中可以正党起振。在液相中，应用此云母石英晶振检测了DNA（pCAT）在云母表面的吸附过程。并与原子力显微镜（AFM）联用观察了DNA在云母表面吸附的物理图象；直接证明了二价锰离子在DNA吸附于云母表面过程中的固定作用。研究了水相中2-巯基苯并咪唑的电化学氧化过程，考察了pH值，浓度的影响。应用EQCM监测了此氧化成膜的过程。结果表明此反应为一电子过程。并结合表面光电子能谱（XPS）对此氧化膜进行了初步表征。应用EQCM研究了核黄素RF在金电极度上的吸附行为和电化学行为。考查了pH值、浓度和扫速对RF的吸附行为和电化学行为的影响。在pH ≤ 9.71下得到可逆的循环伏安图；而pH > 9.71时RF不发生电化学反应；最大电流响应在pH = 8.0。当RF浓度小于1.0 * 10~(-4)mol/L(pH = 6.92)时，电流与扫速平方根成正比关系，相反，浓度大于此值则电流与扫速成正比关系。在辅酶Q_0水溶液的电化学研究中，由伏安曲线得到Q_0的电位～pH图，并以此分析了不同pH值下的Q_0的存在形式，求算了Q_0的酸解常数。研究还表明了辅酶Q_0在金电极上的吸附行为随pH的变化而不同。另外还应用EQCM研究了多晶金电极度在盐酸中的阳极度溶解行为，证明此过程是三电子过程。并发现生物素具有抑制金电极度阳极度溶解的作用。

在辉光放电中六甲基环三硅氧烷聚合的研究

I不同等离子气体对辉光放电聚合物淀积速率的影响 采用H_2、He、N_2、O_2和Ar作为等离子气体，在外部电极电容耦合式反应器中进行了六甲基环三硅氧烷和丙烯的等离子体聚合反应。实验结果表明，这两类性质完全不同的单体在不同等离子气体中聚合时，聚合物淀积速率的大小顺序和八氟环丁烷单体时一样，显示出某种规律性，按淀积速率大小排列，都有He > Ar，H_2 > N_2 > O_2。用磁撞理论解释这种规律时，发现等离子气体分子的质量是影响聚合物淀积速率的主要因素，计算结果和实验结果有好的一致性。II反应参数对六甲基环三硅氧烷辉光放电聚合反应规律及聚合物结构和性能的影响 采用外部电容耦合式RF辉光放电装置进行了六甲基环三硅氧烷的等离子体聚合，用IR、XPS、PGC/MS等方法对聚合物结构进行了表征，并推断了聚合反应历程。观察到使用H_2和O_2为等离子气体时，聚合物的C/Si比较高，并证实这是由于聚合物内存在较多短碳链的结果。从IR、ESR和PGC/MS结果，推断了聚合反应按三种历程进行。TG测试表明，使用惰性等离子气体或者升高放电功率可以使聚合物的热稳定性得到改进。本文还测定了聚合膜对水的接触角，并计算了聚合物的表面能，结果表明在H_2和惰性气体中制备的聚合膜有好的疏水性。III在反应性气体N_2和NH_3中D_3的辉光放电聚合反应 采用N_2和NH_3为等离子气体，在外部电极电容耦合式RF辉光放电装置中进行了六甲基环三硅氧烷的等离子体聚合。用IR、XPS等方法对聚合物结构进行了表征，并推断了N_2和NH_3参加聚合反应的机构。结果表明，N在聚合物中的存在形式为C = NH，随D_3/NH_3比的减小，聚合物的N含量增大，Si-H基团增多。在含氮气体中制备的膜都具有对基质的好的附着性。另外，本工作还进行了聚合物的热失重分析，测定了聚合物对水的接触角，计算了聚合物的表面能，结果表明，在NH_3中制备的聚合膜都具有好的疏水性。IV六甲基环三硅氧烷等离子体聚合膜的应用 在结构研究的基础上，本文讨论了六甲基环三硅氧烷等离子体聚合膜的某些应用，如耐热膜，绝缘膜等，重点讨论了在钟罩式RF辉光放电装置中制备的D_3等离子体聚合复合膜在气体分离方面的应用。结果表明，选择适当的条件可以合成耐热温度达300 ℃，对水的接触角超过100°，电阻系数达10~(19)数量级，以及α > 2，Jo_2在10~(-5)数量级的膜。光进行预处理，后进行等离子体聚合同样可以制得α > 2，Jo_2在10~(-5)数量级的气体分离膜。V等离子体聚合和等离子体曝露聚合对产物结构的影响 在外部平行板式电极的反应装置中进行了六甲基环三硅氧烷和八甲基环四硅氧烷的等离子体曝露聚合反应，并将反得聚合物与相应的等离子体聚合物作了比较。结果表明，两种单体都不能进行后聚合反应，未找出离子历程的证据，与此相反，在结构研究的基础上，提出了自由基历程，给前几部分的历程推导予以了支持。等离子体聚合为原子聚合，而等离子体曝露聚合中只有一部分为原子聚合，等离子体曝露聚合制备的产物的热稳定性比等离子体聚合物差，但线性较好。在非辉光区和弱辉光区可以制备近似结性的聚合物。本工作绝大部分内容还未有文献报导，其中I、III、IV部分还未有文献报导。

含氰基有机化合物的等离子体聚合及电学性能研究

I、等离子体聚合TCNQ、TCNE薄膜采用内部电极、电容耦合式、钟罩型RF等离子体聚合装置，在不同的放电功率下，首次进行了TCNQ（四氰基二甲苯醌）、TCNE（四氰基乙烯）的等离子体聚合，并利用红外光谱（IR）、紫外光谱（UV）、元素分析、X线光电子能谱（XPS）对所得聚合物的化学结构进行了表征。结果表明，在TCNQ、TCNE的等离子体聚合物中存在着较大范围的π电子共轭结构体系。通过对其聚合物薄膜的电学性能研究结果发现，随聚合反应条件不同，所制得的聚合物膜电导率在10~（-10）～ 10~（-6）scm~(-1)范围内变化，并且发现这种等离子体聚合膜具有典型的p-型半导体特征，由这些等离子体聚合物薄膜制备的Al电极/聚合物膜/ITO电极夹层元件，在无光照射的暗状态时，都具有较优良的单向导电的整流特性，并且在白色光的照射下，能够产生光生电动势而显示出较好的光电转换特性。另外，这种聚合物薄膜还具有一定的光电导性。本实验通过研究放电功率对等离子体聚合物化学结构的影响时发现，在较低放电功率时，有利于聚合物中较大范围的π电子共轭结构体系的形成。相应的聚合物膜电学性能研究表明，在较低放电功率下制得的聚合物膜具有更优良的电学性能，如在5W低放电功率下制得的TCNQ聚合物薄膜的电导率可达10~（-6）scm~(-1)，并且由其制备的夹层元件显示出优良的整流特性，当在白色光照射下，光电转换效率可高达10~（-3）%， 这在目前有机太阳能电池研究中，也属相当优良的有机光电转换材料之列。II、起始单体的化学结构对聚合物膜的结构及电学性质影响利用与I同样的实验方法，选用了一些具有不同化学结构的含氰基有机化合物为起始单体[TCNQ、TCNB（四氰基苯）、邻苯二甲腈、TCNE、二氨基马来腈、乙腈]，进行了等离子体聚合，并研究了起始单体结构对聚合物化学结构及电学性质的影响。结果表明，含苯环的氰基化合物在等离子体聚合过程中，具有大π电子共轭结构的苯环保持较好，并能够通过打开C≡N三键向更大范围延续，结果导致相应的等离子体聚合物膜具有较高的电导率，并且由这些聚合物膜制备的Al/聚合物膜/ITO夹层元件显示出优良的整流特性和光电转换性能。相反，当起始单体中的H原子含量较高时，就会导致相应聚合物中π电子共轭链段较短，相应的聚合物也就显示出较差的电学性质。另外，为提高等离子体聚合膜的电学性能，还进行了TCNQ与铜的乙酰丙酮络合物（CuAA）的等离子体共聚合，结果发现聚合膜电学性能明显改善。III、在辉光放电中乙腈等离子体聚合反应历程的研究采用外部电极、电容耦合式、管状RF等离子体聚合装置，在不同放电功率下，不同等离子气体以及不同等离子气体/单体比的反应条件下进行了等离子体聚合。通过考察聚合物膜的淀积规律和红外光谱测试与元素分析提供的聚合物化学结构数据，研究了乙腈在辉光放电中的聚合反应历程。实验结果表明，在低能量下，乙腈的等离子体聚合主要是通过脱氢引发进行的，而在高能量下，通过打开C≡N三键而进行聚合的几率将增大。