Single layer silicon photonic crystal slab

We present here the fabrication and characterization of single layer silicon photonic crystal mirror on a silicon-on-insulator wafer. By a combination of electron beam lithography, fast atom beam etching with deep reactive ion etching, silicon photonic crystal slabs are achieved on 260 nm freestanding silicon membrane and sandwiched with air on the top and bottom. Their high refractive index contrasts enable photonic crystal slabs function as dielectric mirrors for externally incident light. The optical performances of fabricated photonic crystal slabs can be tuned by varying the width of separation grooves or the air-hole size, which represents a significant advantage of offering various approaches for optical response control.     

Fabrication of Silicon-Blazed Gratings for Couplers

To our knowledge, no blazed grating has been fabricated in silicon (Si) at a pitch of less than half a micron. In this article, we report the fabrication of Si-blazed gratings at the period of 400 nm, using electron beam lithography and ion beam etching techniques. The blazed grating is extremely useful as a grating coupler in integrated optics, operating at the telecommunication wavelength of 1.3 mum, because very high output efficiency of the grating coupler is expected. This will allow coupling to thin film devices in silicon, previously not regarded as promising because coupling to them was very inefficient.     

Fabrication of Silicon-Blazed Gratings for Couplers

To our knowledge, no blazed grating has been fabricated in silicon (Si) at a pitch of less than half a micron. In this article, we report the fabrication of Si-blazed gratings at the period of 400 nm, using electron beam lithography and ion beam etching techniques. The blazed grating is extremely useful as a grating coupler in integrated optics, operating at the telecommunication wavelength of 1.3 mum, because very high output efficiency of the grating coupler is expected. This will allow coupling to thin film devices in silicon, previously not regarded as promising because coupling to them was very inefficient.     

Si layer transfer to InP substrate using low-temperature wafer bonding

Using a low-temperature wafer bonding process, InP substrates are bonded to silicon-on-insulator (SOI) substrates at 220 °C. A combination of oxygen plasma and chemical treatment results in a direct contact bonding at room temperature. After the bonding process at 220 °C for 45 min, removal of the Si handle substrate by sacrificial etching of the buried oxide layer in SOI, results in a thin membrane of Si robustly bonded to InP. The thin Si membrane bonded to InP shows uniformly bonded interface under high-resolution electron microscopy. Micro-Raman analysis has also been carried out to study the bonded interface. I-V characteristics of the bonded structures suggest that such bonding and layer transfer processes are suitable for device integration.     

Freestanding circular GaN grating fabricated by fast-atom beam etching

We report here a top-down process for fabricating a freestanding circular GaN grating. The circular gratings are defined by electron-beam lithography and realized by fast-atom beam (FAB) etching. The silicon substrate below the GaN grating region is completely removed to make the circular grating suspended in space. The optical responses of the fabricated GaN gratings are characterized in reflectance measurements. The polarization-independent responses of circular gratings are experimentally demonstrated, corresponding well with the theoretical prediction. This work represents an important step in combining GaN-based material with freestanding nanostructures.     

偏晶向(111)硅片闪耀光栅的制作

硅光栅的制作可以利用湿法腐蚀体硅工艺.湿法腐蚀利用硅的各向异性,由硅的晶面形成光栅工作凹槽,利用湿法工艺可以制作在不同光谱波段内工作的闪耀光栅.设计了一种利用偏晶向(111)硅片制作闪耀光栅的方法,使用这种方法可以批量制作闪耀角度较小的光栅.利用扫描电子显微镜(SEM)进行了光栅表面形貌测试,试验结果表明,制作的硅光栅样片具有良好光学特性的反射表面和光栅槽形.硅闪耀光栅可以被用来制作微型光谱仪、滤光器等微型仪器或器件.     

Dual material insulator SOI-LDMOSFET: A novel device for self-heating effect improvement

The silicon-on-insulator (SOI) power devices show good electrical performance but they suffer from inherent self-heating effect (SHE), which limits their operation at high current levels. The SHE effect is because of low thermal conductivity of the buried oxide layer. In this paper we propose a novel silicon on insulator lateral double diffused MOSFET (SOI-LDMOSFET) where the buried insulator layer under the active region consists of two materials in order to decrease the SHE. The proposed structure is called dual material buried insulator SOI-LDMOSFET (DM-SOI). Using two-dimensional and two-carrier device simulation, we demonstrate that the heat dissipation and the SHE can be improved in a conventional SOI-LDMOSFET by replacement of the buried oxide with dual material buried insulator (silicon nitride and silicon oxide) beneath the active region. The heat generated in the active silicon layer can be flowed through the buried silicon nitride layer to the silicon substrate easily due to high thermal conductivity of silicon nitride. Furthermore, the channel temperature is reduced, negative drain current slope is mitigated and electron and hole mobility is increased during high-temperature operation. The simulated results show that silicon nitride is a suitable alternative to silicon dioxide as a buried insulator in SOI structures, and has better performance in high temperature.     

硬X射线相位光栅的设计与研制

针对在普通实验室和医院实现40—100keVX射线相衬成像的需求,考虑到成像系统参数、X射线源空间相干特性及光栅衍射效率,设计出硅基相位光栅结构参数.利用我们已发展的光助电化学刻蚀技术研制出直径为5英寸的相位光栅,其空间周期为5.6μm,线宽为2.8μm,深度为40—70μm.在理论分析的基础上,通过提高硅片两端有效工作电压和修正Lehmann电流密度公式,解决了实际刻蚀过程中出现的钻蚀问题.由实验结果可知,本方案对制作大面积高精度相位光栅十分有效。     

Development of novel flexible black silicon

We report a new type of black silicon: flexible black silicon. A silicon-on-insulator (SOI) wafer is irradiated by automatically scanning a femtosecond laser and then split by etching out the SOI silica middle layer. Large-area, uniform micro spikes on the surface of a very thin flexible silicon layer are obtained. The black silicon shows good flexibility and optical properties. The absorption spectrum of the flexible black silicon is as high as 97% in the visible and insensitive to the change of the incident angle of the light, which makes it a potential good candidate as an absorber for the solar-thermo generator.     

Breakdown voltage model and structure realization of a thin silicon layer with linear variable doping on a silicon on insulator high voltage device with multiple step field plates

Based on the theoretical and experimental investigation of a thin silicon layer(TSL) with linear variable doping(LVD) and further research on the TSL LVD with a multiple step field plate(MSFP),a breakdown voltage(BV) model is proposed and experimentally verified in this paper.With the two-dimensional Poisson equation of the silicon on insulator(SOI) device,the lateral electric field in drift region of the thin silicon layer is assumed to be constant.For the SOI device with LVD in the thin silicon layer,the dependence of the BV on impurity concentration under the drain is investigated by an enhanced dielectric layer field(ENDIF),from which the reduced surface field(RESURF) condition is deduced.The drain in the centre of the device has a good self-isolation effect,but the problem of the high voltage interconnection(HVI) line will become serious.The two step field plates including the source field plate and gate field plate can be adopted to shield the HVI adverse effect on the device.Based on this model,the TSL LVD SOI n-channel lateral double-diffused MOSFET(nLDMOS) with MSFP is realized.The experimental breakdown voltage(BV) and specific on-resistance(R on,sp) of the TSL LVD SOI device are 694 V and 21.3 ·mm 2 with a drift region length of 60 μm,buried oxide layer of 3 μm,and silicon layer of 0.15 μm,respectively.     

XUV成像系统中像传递函数研究用的Si刻蚀膜

 研制具有网格或条状图形的Si刻蚀膜靶，用于XUV系统中像传递函数的研究。在自截止腐蚀工艺制备Si平面薄膜的基础上，结合离子束刻蚀工艺，获得刻蚀深度为1.0 μm左右，网格尺寸为25 μm×25 μm，或条状线宽为5 μm的Si刻蚀膜；测量了Si刻蚀膜的形貌和刻蚀深度；研究了离子束刻蚀参数对图形形貌的影响。并介绍采用两种靶型获得的像传递函数信息。     

SOIM新结构的制备及其性能的研究

制备在以SiO2为绝缘埋层的SOI材料上的电子器件存在着自加热问题.为减少自加热效应和满足一些特殊器件/电路的要求，利用多孔硅外延转移技术制备出以二氧化硅和氮化硅为多绝缘埋层的SOI新结构.高分辨率透射电镜和扩展电阻测试结果表明得到的SOIM新结构具有很好的结构和电学性能，退火后的氮化硅埋层为非晶结构.     

双面阶梯埋氧层部分SOI高压器件新结构

提出了双面阶梯埋氧层部分绝缘硅(silicon on insulator,SIO)高压器件新结构. 双面阶梯埋氧层的附加电场对表面电场的调制作用使表面电场达到近似理想的均匀分布, 耗尽层通过源极下硅窗口进一步向硅衬底扩展, 使埋氧层中纵向电场高达常规SOI结构的两倍, 且缓解了常规SOI结构的自热效应. 建立了漂移区电场的二维解析模型, 获得了器件结构参数间的优化关系. 结果表明, 在导通电阻相近的情况下, 双面阶梯埋氧层部分SOI结构击穿电压较常规SOI器件提高58％, 温度降低10—30K. 关键词： 双面阶梯 埋氧层 调制 自热效应     

电致发光的完全悬空超薄硅衬底氮化镓基蓝光LED器件的制备与表征

为提升硅衬底氮化镓基LED(发光二极管)器件的光电性能和出光效率,本文提出了一种利用背后工艺实现的悬空薄膜蓝光LED器件.结合光刻工艺、深反应离子刻蚀和电感耦合等离子体反应离子刻蚀的背后工艺,制备了发光区域和大部分正负电极区域的硅衬底完全掏空,并减薄大部分氮化镓外延层的悬空薄膜LED器件.对悬空薄膜LED器件进行三维形...     

新型SOANN埋层SOI器件的自加热效应研究

本文提出了一个新型的SOI埋层结构SOANN (silicon on aluminum nitride with nothing),用AlN代替传统的SiO₂材料,并在SOI埋氧化层中引入空洞散热通道. 分析了新结构SOI器件的自加热效应.研究结果表明:用AlN做为SOI埋氧化层的材料, 降低了晶格温度,有效抑制了自加热效应.埋氧化层中的空洞,可以进一步提供散热通道, 使埋氧化层的介电常数下降,减小了电力线从漏端通过埋氧到源端的耦合, 有效抑制了漏致势垒降低DIBL(drain Induced barrier lowering)效应.因此,本文提出的新型SOANN结构可以提高SOI器件的整体性能,具有优良的可靠性.     

Compound buried layer SOI high voltage device with a step buried oxide

A silicon-on-insulator (SOI) high performance lateral double-diffusion metal oxide semiconductor (LDMOS) on a compound buried layer (CBL) with a step buried oxide (SBO CBL SOI) is proposed.The step buried oxide locates holes in the top interface of the upper buried oxide (UBO) layer.Furthermore,holes with high density are collected in the interface between the polysilicon layer and the lower buried oxide (LBO) layer.Consequently,the electric fields in both the thin LBO and the thick UBO are enhanced by these holes,leading to an improved breakdown voltage.The breakdown voltage of the SBO CBL SOI LDMOS increases to 847 V from the 477 V of a conventional SOI with the same thicknesses of SOI layer and the buried oxide layer.Moreover,SBO CBL SOI can also reduce the self-heating effect.     

光梯度力驱动的纳米硅基光开关

通过一道光改变另一道光的传输路线是光子集成网络中重要而长远的目标, 然而, 由于硅材料的光学非线性较弱, 在硅材料上实现开关的全光控制难以实现. 因此本文提出了一种由光梯度力驱动的纳米硅基光开关, 实现了硅基光开关的全光控制. 该光开关由一个部分悬空的微环谐振器和一个交叉波导结构构成, 当通入一道控制光时, 悬空的微环谐振器在光梯度力的作用下发生弯曲, 微环谐振器的谐振波长随之发生变化, 从而实现光信号的传输路线发生改变. 该光开关利用纳米光子制造技术在标准绝缘体上硅晶圆上制造, 实验数据得出其最小消光比为10.67 dB, 最大串扰为 -11.01 dB, 开关时间分别为180 ns和170 ns. 该光开关具有尺寸小, 响应速度快, 低损耗和可拓展等优点, 在片上集成光路、高速信号处理以及下一代光纤通信网络中具有潜在应用.     

光栅光阀器件的结构改进与制作工艺研究

根据光栅光阀的工作原理,在结构上对传统的光栅光阀器件进行了改进,分析了改进后光栅光阀器件的光学特性、结构特性,以及制作工艺流程.改进后的光栅光阀结构中硅基底上设有二氧化硅隔离层,隔离层上沉积无定形硅作为牺牲层,可动梁的材料是氮化硅,固定梁为蒸镀的金属铝层.通过离子刻蚀的方法刻蚀图形,用化学腐蚀方法掏空牺牲层得到所需桥梁状结构.研究表明改进后的器件黑区范围小,驱动电压较低,光学效率较高,具有潜在的应用前景.     

全息离子束刻蚀衍射光栅

全息离子束刻蚀衍射光栅集中了机械刻划光栅的高效率和全息光栅的无鬼线、低杂散光、高信噪比的优点．全息离子束刻蚀已作为常规工艺手段应用于真空紫外及软x射线衍射光栅的制作．文章对全息离子束刻蚀衍射光栅的制作方法、主要类型、研究现状和应用进行了综述．     

Phenomena in silicon nanostructure devices

In nanostructures, whenever the electron mean-free-path exceeds the appropriate dimensions of the device structure, quantum natures may dictate the physical properties of devices. Among many important issues, some are selected in this work, whereas others, such as the reduction of dielectric constant, the increased binding energy of dopants, etc., are discussed briefly with references for further considerations. In the past several years, resonant tunneling via nanoscale silicon particles imbedded in an oxide matrix has shown striking similarity to the so-called soft breakdown (SBD), an important current subject in devices with ultrathin oxide gates. The relevance in applying results discussed here to SBD is discussed. A Si/O superlattice, a particular form of a new type of superlattice, semiconductor-atomic superlattice (SAS), is fully discussed. This Si/O superlattice can be used in silicon quantum and light-emitting devices. A diode structure with green electroluminescence has been life-tested for more than one year without degradation. High-resolution TEM shows defect density below 10⁹/cm². Preliminary calculation shows that the Si/O complexes result in a barrier height of 0.9 eV for silicon, sufficient for an epitaxially grown SOI, which is potentially far better than the SOI using buried oxide implantation followed by high temperature anneal. Received: 14 April 2000 / Accepted: 17 April 2000 / Published online: 6 September 2000