Si/Si直接键合界面的FTIR和XPS研究

通过新颖的键合方法实现了Si/Si直接键合.采用傅里叶红外透射谱(FTIR)对Si/Si键合界面进行了研究,结果表明,高温退火样品的界面组分为Si和O,无OH和H网络存在.X射线光电子谱(XPS)测试结果进一步表明,界面主要为单质Si和SiOx混合网络,且随着退火温度的升高,界面层Si-Si直接成键的密度也越高.     

Analysis of Compressively Strained GaInAsP–InP Quantum-Wire Electro-Absorption Modulators

Performance of compressively strained (CS) GaInAsP-InP quantum-wire (QWR) electro-absorption modulators (EAMs) is theoretically studied using an eight-band kldrp model. An empirical relationship is proposed for the quantum-confined Stark shift in QWR EAMs. The accuracy of this relationship is verified by comparing with numerical data. The effects of the variation of different device parameters on the absorption spectra are investigated. The absorption peaks are found to be stronger in narrower QWRs with strain-compensating barriers. Comparison of the extinction ratio with that of similar quantum-well EAMs show that, in spite of the lower in-plane filling factor, QWR EAMs exhibit a higher extinction ratio. Effect of fluctuation of wire width on the absorption spectrum of QWRs has been studied. The proposed QWR EAMs are suitable for photonic integrated circuits (PICs) fabricated by electron-beam lithography, reactive-ion etching, and two-step epitaxial growth. Due to the nature of the integration in such structures, the QWR EAMs are not required to be polarization-insensitive. On the contrary, the QWR EAMs are naturally tuned to the polarization of the output of the CS QWR lasers, fabricated on the same PIC, leading to an enhancement of the absorption strength. Moreover, the QWR EAMs, integrated with QWR lasers, offer low insertion loss.     

Room-Temperature Continuous-Wave Electrically Injected InP–GaInAsP Equilateral-Triangle-Resonator Lasers

Equilateral-triangle-resonator (ETR) microlasers with an output waveguide connected to one of the vertices of the ETR are suitable to be a light source for photonic integrated circuits. InP-GaInAsP ETR lasers with side length from 10 to 30 mum and the output-waveguide width of 1 or 2 mum are fabricated using standard photolithography and inductively coupled-plasma etching techniques. Continuous-wave electrically injected 1520-nm ETR laser with 20-m sides is realized with the maximum output power 0.17 and 0.067 mW and the threshold current 34 and 43 mA at 290 K and 295 K, respectively.     

A Monolithic MQW InP–InGaAsP-Based Optical Comb Generator

We report the first demonstration of a monolithic optical-frequency comb generator. The device is based on multisection quaternary/quaternary eight-quantum-well InP-InGaAsP material in a frequency-modulated (FM) laser design. The modulation is generated using quantum-confined Stark-effect phase-induced refractive index modulation to achieve fast modulation up to 24.4 GHz. The laser was fabricated using a single epitaxial growth step and quantum-well intermixing to realize low-loss phase adjustment and modulation sections. The output was quasicontinuous wave with intensity modulation at less than 20% for a total output power of 2 mW. The linewidth of each line was limited by the linewidth of the free running laser at an optimum of 25 MHz full-width at half-maximum. The comb generator produces a number of lines with a spacing exactly equal to the modulation frequency (or a multiple of it), differential phase noise between adjacent lines of -82 dBc/Hz at 1-kHz offset (modulation source-limited), and a potential comb spectrum width of up to 2 THz (15 nm), though the comb spectrum was not continuous across the full span.     

Nested-Ring Mach–Zehnder Interferometer in Silicon-on-Insulator

For the first time, a nested-ring Mach-Zehnder interferometer (MZI) on silicon-on-insulator is realized using a complementary metal-oxide-semiconductor-based process. In this letter, we verify that the device operates in two modes: the inner-loop resonance dominant mode due to strong build-up inside the inner-ring, and the double-Fano resonances mode due to strong light interaction with the outer loop. The results show that the inner-loop resonance is highly sensitive to the MZI arm imbalance compared to the double-Fano resonance mode. Based on these considerations, we obtain a good fit between theory and experiment.     

硅基板激光微熔覆电子浆料制备导体的研究

激光微细熔覆电子浆料技术是一种新型的柔性布线技术，采用激光精密加工系统对电子浆料进行处理以制备导线，具有柔性化程度高、电路图形设计、修改简捷、适合小批量生产等优点。特别是可以制备最小线宽为20 μm左右的导体，突破了传统丝网印刷工艺制备导线宽度的极限。利用激光微细熔覆工艺在单晶硅基板上制备出了银导线。所制备导线的最小宽度在30 μm左右，其电阻率和块状银在同一个数量级，能够满足应用要求。利用悬挂法测定其与硅基板的结合强度在兆帕数量级，与传统丝网印刷工艺相当。相关的工艺实验还表明，导体线宽随激光功率密度的增加而增加，随激光扫描速度的增加而减小;对于特定厚度的浆料预置层，激光扫描参数存在一个最佳的范围。激光扫描之后的高温热处理工艺有利于导线导电性能及其与硅基板的结合强度的进一步提高。     

Radio-Frequency-Noise Characterization and Modeling of Type-II InP–GaAsSb DHBT

This letter presents the first characterization of radio-frequency noise of type-II InP-GaAsSb double-heterojunction bipolar transistors (DHBTs) from 2 to 24 GHz. Its small-signal noise equivalent model is developed and verified with the experimental data. The noise performance of the type-II InP-GaAsSb HBT is also compared with the type-I InP-InGaAs HBT with similar cutoff frequencies larger than 300 GHz. The analysis shows that the particular type-II transistor under test has higher noise than its counterpart type-I device primarily due to the difference of dc current gain.     

光泵浦Si衬底GaN基回音壁模式微盘谐振腔激光器

氮化镓基微盘结构光学谐振腔具有波长选择范围宽、模式体积小和激射阈值低等特点,其在腔量子电动力学、低阈值激光器、生物传感器等方面具有重要的研究价值.通过优化制备微盘的干法刻蚀工艺及选择性湿法腐蚀技术,制备出侧壁陡峭且光滑的高Q值Si衬底GaN基回音壁模式微盘谐振腔,该微盘谐振腔的制备工艺简单、表面损伤小.在室温、266 nm短波长激光泵浦条件下,微盘谐振腔激光器实现了激射,阈值为2.85 MW/cm2,Q值达到2161.     

Effect of Silicon-on-Insulator Substrate on Residual Strain in 3C-SiC Films

One group of SiC films are grown on silicon-on-insulator (SOI) substrates with a series of silicon-over-layer thickness.Raman scattering spectroscopy measurement clearly indicates that a systematic trend of residual stress reduction as the silicon over-layer thickness decreases for the SOI substrates.Strain relaxation in the SiC epilayer is explained by force balance approach and near coincidence lattice model.     

SOI衬底对3C-SiC异质外延薄膜内残存应力的影响

在一组具有不同厚度表层硅的SOI衬底上异质外延SiC薄膜.Raman测试结果表明,SiC薄膜中的残存应力随着表层硅厚度的减薄而降低.采用力平衡原理和重合位置点阵模型对SiC外延层中的应力释放现象进行了解释.     

High temperature current–voltage characteristics of InP‐based tunnel junctions

In this paper, we present temperature‐dependent current–voltage measurements of tunnel junctions lattice matched to InP at temperatures ranging from room temperature to 220 °C. Temperature‐dependent tunneling properties were extracted by fitting the current–voltage characteristics using a simple analytical formula. Three different designs of tunnel junction were characterized, including a bulk InAlGaAs tunnel junction, an InAlGaAs tunnel junction with InAlAs cladding layers and an InGaAs/InAlGaAs quantum‐well tunnel junction. Each device exhibited different temperature dependence in peak tunnel current and excess current, with the quantum‐well tunnel junction exhibiting the greatest temperature sensitivity. We use a non‐local tunneling model, in conjunction with a numerical drift‐diffusion solver, to explain the performance improvement available by using double heterostructure cladding layers around the junction region, and use the same model to explain the observed temperature dependence of the devices. Copyright © 2014 John Wiley & Sons, Ltd.     

Picometer Resolution Wavelength Tracking in the C -Band Using an InP–InGaAsP Dual-Slab Interferometer

A simple III-V semiconductor dual-slab waveguide interferometer is demonstrated which can detect picometer level changes in the C-band laser wavelength. Optical path length imbalance between the two single-slab waveguide modes provides the primary mechanism for detection. The dual-mode output field phase change differences due to input wavelength changes are encoded in shifts in the device output far-field interference pattern. The device detects path length dependent wavelength changes with a phase change difference sensitivity of around 660 mrad/nmldrmm at 1.55 mum and a phase detection floor of plusmn1 mrad. The transverse electric and transverse magnetic polarization responses are approximately equivalent.     

Si上Si_(1-x-y)Ge_xC_y三元合金薄膜的生长

研究了 Si衬底上 Si Ge C合金薄膜的生长。以 C2 H4 为 C源、采用快速加热超低压化学气相淀积 (RTP/VL P- CVD)的非平衡生长技术 ,在 Si(10 0 )衬底上生长出具有一定代位式 C含量的硅基 Si Ge C合金。实验表明 :较低的生长温度和较高的 Si H4 /C2 H4 流量比有利于代位式 C原子的形成和材料晶体质量的提高。     

Temperature-Dependence of Ge on Si p–i–n Photodetectors

We investigate the temperature dependence of germanium on silicon p–i–n photodetectors in terms of both dark current density and near-infrared responsivity. The dark current increases by nearly a factor 1.6 every 10 $^{circ} $C, consistently with carrier generation in the space charge region. The responsivity has a complex trend, its temperature variation depending on wavelength and on the germanium quality. Detectors with a large defect density in the active layer exhibit a reduced responsivity as the temperature increases.      

Stable Stretchable Silver Electrode Directly Deposited on Wavy Elastomeric Substrate

We demonstrated a stable operation of stretchable silver (Ag) electrodes under fast cycling strain stress conditions. Relatively thick Ag electrodes (700 nm) were directly deposited on an elastomeric polydimethylsiloxane (PDMS) substrate with vertical wavy patterns that were formed by using an aluminum mold. The large surface roughness of PDMS substrate that was transferred from an intentionally roughened mold surface enhanced the adhesion between thick electrode and PDMS layer. Top PDMS layer was coated on the Ag electrode for encasement. During a slow stretching test (16.7 $muhbox{m/s}$), the resistance of the Ag electrode on the wavy substrate was increased only by three times for 50% tensile strain. The change in Ag electrode resistance was monitored during 10 000 times of fast (1 mm/s) cycling of 10% tensile strain. The maximum resistance was increased by less than five times during the stress test and returned to its initial value after the stress was removed.      

Dependence of the Luminescence Properties of Ordered Groups of Ge(Si) Nanoislands on the Parameters of the Pit-Patterned Surface of a Silicon-on-Insulator Substrate

Semiconductors - This paper presents the results of studies of the luminescence properties of structures with Ge(Si) quantum dots (QDs), in which the pit-patterned surface of a silicon-on-insulator...     

Demonstration and Performance Assessment of Large Format InP–InGaAsP Quantum-Well Infrared Photodetector Focal Plane Array

There have been various studies showing that InP-InGaAs quantum-well infrared photodetectors (QWIPs) are potential alternatives to AlGaAs-GaAs QWIPs in the long wavelength infrared (LWIR) band, especially for applications requiring high responsivity. Being on InP substrate, this material system also offers lattice matched mid-wavelength infrared (MWIR)/LWIR dual band QWIP stack when it is used with the AlInAs-InGaAs system. It is desirable to extend the cut-off wavelength of InP based LWIR QWIPs to , which can be accomplished by replacing the QW material with InGaAsP. In this paper, we report the first InP-InGaAsP QWIP focal plane array (FPA). The 640 512 FPA displayed remarkably low noise equivalent temperature difference (NETD) with very short integration times (46 mK at 66 K with and f/1.5 optics). The results show that these QWIPs can be operated with high responsivity (1 A/W) while offering bias adjustable gain in a wide range where the detectivity is almost constant at a reasonably high level.     

硅衬底上异质外延生长硅化钴研究进展

综述近年国内外在CoSi2／Si异质外延生长技术领域的研究进展,在半导体衬底上异质外延具有优良导电特性的金属硅化物,从基础研究和技术发展两方面都具有重要价值。利用Co／Ti／Si多层薄膜固相反应实现CoSi2／Si异质外延,是近年取得重要进展的新方法。应用这种方法在（111）和（100）硅衬底上都可实现CoSi2外延生长,无需在超高真空下进行,与硅器件基本工艺相容性好,可形成自对准硅化物接触结构,对发展新器件制造技术有重要作用。在简要介绍分子束外延和离子合成CoSi2外延薄膜生长技术后,重点介绍和评述新型固相异质外延方法的工艺技术、机理和应用研究进展。     

Very High-Temperature Joints Between Si and Ag–Copper Substrate Made at Low Temperature Using InAg System

We present a fluxless bonding process between silicon and Ag–copper dual-layer substrate using electroplated indium/silver solder. The nucleation mechanism of In plated over Ag layer is first investigated. It is interesting to discover that In atoms react with underlying Ag to from ${hbox {AgIn}}_{2}$ compound layer during electroplating. A novel Ag laminating technique on Cu substrates is developed. The Ag cladding functions as a strain buffer to manage the large mismatch in coefficient of thermal expansion (CTE) between semiconductors such as Si (3 ${hbox {ppm}}/^{circ}{hbox {C}}$) and Cu (17 ${hbox {ppm}}/^{circ}{hbox {C}}$) substrates. To bond Si chips to the Ag layer on copper substrates, In-based alloy (InAg) is used. A fluxless bonding process is developed between Si/Cr/Au/Ag and Cu/Ag/In/Ag. The process is performed in 50-militorr vacuum to suppress solder oxidation. No flux is used. The resulting joints consist of three distinct layers of Ag, ${hbox {Ag}}_{2}{hbox {In}}$ and Ag. Microstructure and composition of the joints are examined using scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX). Bonded samples are further annealed to convert the ${hbox {Ag}}_{2}{hbox {In}}$ phase into solid solution phase (Ag). The joint has a melting temperature above 850 $^{circ}{hbox {C}}$. This technique presents our success in overcoming the very large CTE mismatch between silicon and copper. It can be applied to mounting numerous high-power silicon devices to Cu substrates for various industrial applications.      

硅衬底GaN基LED的研究进展

与蓝宝石衬底相比，硅衬底具有低成本、大面积、高质量、导电导热性能好等优点，普遍认为使用Si片作GaN薄膜衬底有可能实现光电子和微电子的集成，因此Si基GaN的研究受到了广泛关注。本文回顾了Si衬底GaN基LED的研究进展，同时简要介绍了在Si衬底上制备GaN基LED的实验结果，及研制出工作电压为3．6V、串联电阻为31Ω、输出功率近1mW的Si衬底GaN基蓝光LED。