SIMOX SOI埋氧注氮工艺对埋氧中固定正电荷密度的影响

在SIMOX SOI材料的埋氧中注氮是为了增强该类材料的抗辐射能力.通过C-V研究表明，对于埋氧层为150 nm的SIMOX SOI材料来说，当在其埋氧中注入4×10¹⁵cm^-2剂量的氮后，与未注氮埋氧相比，注氮埋氧中的固定正电荷密度显著增加了；而对于埋氧层为375nm的SIMOX SOI材料来说，当注氮剂量分别为2×10¹⁵cm^-2和3×10¹⁵cm^{-2关键词： SIMOX 埋氧 注氮 固定正电荷密度}     

单层MoSe2单晶的光学及电学性能探究

采用Au箔作为生长衬底,通过化学气相沉积法制备了高质量的单层MoSe₂单晶.通过光学显微镜、扫描电子显微镜、扫描透射电子显微镜等对其形貌和结构进行了表征,研究了单层MoSe₂单晶的光学及电学特性.结果表明：单层MoSe₂具有非线性光学特性,并具有直接带隙结构(带隙宽度约为1.56 eV)及较好的光致发光特性.当其作为场效应晶体管器件的半导体沟道材料时,器件的载流子迁移率为1.6 cm²/(V·s),开关比约为10⁴.     

硅直接键合界面附近的深能级研究

利用扩展电阻探针（ＳＲＰ）和深能级瞬态谱（ＤＬＴＳ）技术详细研究了直接键合的ｎ－Ｓｉ／ｎ⁺－Ｓｉ界面附近的深能级。实验结果表明，在直接键合的ｎ－Ｓｉ／ｎ⁺－Ｓｉ界面ｎ－Ｓｉ一侧附近可观察到一个明显的电子陷阱Ｅ１（Ｅ_ｃ－０．３９ｅＶ）。Ｅ１可能是由若干个能级位置相近的陷阱迭加而成的，其浓度在１０¹³－１０¹⁴ｃｍ^-3之间。它可能是与制备键合材料的高温（１０００－１１００℃）处理 关键词：     

112型铁基化合物EuFeAs2的单晶生长与表征

铁基超导体中含有一类特殊的112型结构化合物,其层状结构中含有一层锯齿形的As链构型.本文报道了用CsCl助熔剂法生长新型铁基112型EuFeAs₂母体单晶的具体方法,以及对该单晶的结构和物性的详细表征.通过能量色散X射线能谱扫描对单晶样品进行的化学成分分析,以及单晶X射线衍射的结构解析,确定该单晶样品属于EuFeAs₂相,结构精修得到EuFeAs₂具有空间群为Imm2（No.44）的正交晶体结构,晶格常数分别是a=21.285（9）Å,b=3.9082（10）Å,c=3.9752（9）Å.通过低温电阻测量,发现在110 K附近和46 K附近存在两个异常电阻跳变.进一步分析表明,110 K附近存在两个邻近的相变,这两个相变与铁基母体材料中常见的结构相变和Fe²⁺的反铁磁相变相符合.结合磁化率测量分析,可知46 K附近的相变属于Eu²⁺的反铁磁相变.     

(Lu,Y)2SiO5∶Ce3+与SrSO4∶Dy3+材料低温热释光及其测试仪器的研究

为了分析材料在低温下的陷阱能级,获得更多有关缺陷结构的信息,研制了一套由STM32微控制器为核心的低温热释光发光谱测量系统。设计了低温样品室,采用液氮冷却样品;STM32通过控制加热电流,实现样品以恒定速率升温,从而获得低温热释光发光曲线或三维热释光谱。温度测量范围为85~400 K,升温速率范围为0.1~10 K/s。设计了由STM32控制X射线及紫外光源的驱动电路,用于样品的激发。采用高灵敏度CCD实现对三维热释光谱的测量,采用单光子计数器获取二维热释光发光曲线。利用该系统测试了（Lu,Y）₂SiO₅:Ce³⁺（LYSO:Ce³⁺）单晶闪烁体与SrSO₄:Dy³⁺粉末样品的热释光谱及辐射发光光谱。观察到LYSO:Ce³⁺在108,200,380 K左右的热释光峰,发光波长位于390~450 nm之间,是明显的宽带峰。在低温下由于基质的自陷激子（STE）发射所形成的发射峰在166 K时发生猝灭。在309 K时,Ce³⁺发射峰展宽为单一发射峰;SrSO₄:Dy³⁺发光峰温度为178,385 K,发光波长由Dy³⁺离子的能级跃迁决定,在480,575,660,750 nm处呈现窄带发光峰。结果表明,系统人机交互界面友好,实验数据可靠,智能化程度高,操作简单。     

亚毫安阈值的1.3μm垂直腔面发射激光器

设计并研制了室温连续工作的单模13 μm垂直腔面发射激光器（VCSEL）,阈值电流为051 mA,最高连续工作温度达到82℃,斜率效率为029 W/A.采用InAsP/InGaAsP应变补偿多量子阱作为有源增益区,由晶片直接键合技术融合InP基谐振腔和GaAs基GaAs/Al（Ga）As分布布拉格下反射腔镜,并由电子束蒸发法沉积SiO₂/TiO₂介质薄膜上反射腔镜形成13 μm VCSEL结构.讨论并分析了谐振腔模式与量子阱增益峰相对位置对器件性能的影响. 关键词： 垂直腔面发射激光器 晶片直接键合 应变补偿多量子阱     

电离辐射对部分耗尽绝缘体上硅器件低频噪声特性的影响

本文针对辐射前后部分耗尽结构绝缘体上硅(SOI)器件的电学特性与低频噪声特性开展试验研究. 受辐射诱生埋氧化层固定电荷与界面态的影响, 当辐射总剂量达到1 M rad(Si) (1 rad = 10^-2 Gy)条件下, SOI器件背栅阈值电压从44.72 V 减小至12.88 V、表面电子有效迁移率从473.7 cm²/V·s降低至419.8 cm²/V· s、亚阈斜率从2.47 V/dec增加至3.93 V/dec; 基于辐射前后亚阈斜率及阈值电压的变化, 可提取得到辐射诱生界面态与氧化层固定电荷密度分别为5.33×10¹¹ cm^{- 2}与2.36×10¹² cm^-2. 受辐射在埋氧化层-硅界面处诱生边界陷阱、氧化层固定电荷与界面态的影响, 辐射后埋氧化层-硅界面处电子被陷阱俘获/释放的行为加剧, 造成SOI 器件背栅平带电压噪声功率谱密度由7×10^{- 10} V²·Hz^-1增加至1.8×10^-9 V² ·Hz^-1; 基于载流子数随机涨落模型可提取得到辐射前后SOI器件埋氧化层界面附近缺陷态密度之和约为1.42×10¹⁷ cm^-3·eV^-1和3.66×10¹⁷ cm^-3·eV^-1. 考虑隧穿削弱因子、隧穿距离与时间常数之间关系, 本文计算得到辐射前后埋氧化层内陷阱电荷密度随空间分布的变化.     

离子注入形成SOI结构的界面及埋层的俄歇能谱研究

本文中研究了O⁺(200keV,1.8×10¹⁸/cm²)和N⁺(190keV,1.8×10¹⁸/cm²)注入Si形成SOI(Silicon on Insulator)结构的界面及埋层的化学组成。俄歇能谱的测量和研究结果表明:注O⁺的SOI结构在经1300℃,5h退火后,其表层Si和氧化硅埋层的界面存在一个不饱和氧化硅状态,氧化硅埋层是由SiO₂相和这不饱和氧化硅态组成,而且氧化硅埋层和体硅界面不同于表层Si和氧化硅埋层界面;注N⁺的SOI结构在经1200℃,2h退火后,其氮化硅埋层中存在一个富N的疏松夹层,表层Si和氮化硅埋层界面与氮化硅埋层和体硅界面性质亦不同。这些结果与红外吸收和透射电子显微镜及离子背散射谱的分析结果相一致。还对两种SOI结构界面与埋层的不同特征的原因进行了分析讨论。 关键词：     

高温退火对非晶CNx薄膜场发射特性的影响

采用射频磁控溅射方法在纯N₂气氛中沉积了非晶CN_x薄膜样品，并 在真空中退火至900 ℃.对高温退火引起的CN_x薄膜化学成分、键合结构及其场发射特性方面的变 化进行研究.用傅里叶变换红外光谱和x射线光电子能谱分析样品的内部成分及键合结构的变化，其中sp²键及薄膜中N的含量与薄膜的场发射特性密切相关.退火实验的结果表明 高温退火可以导致CN_x薄膜中N含量大量损失，并在薄膜中形成大量sp^{2< 关键词： x薄膜')" href="#">CN_x薄膜 化学键合 退火温度 场致电子发射}     

β-SiC单晶块体拉伸变形行为分子动力学研究

用分子动力学方法研究面心立方SiC(β-SiC)、C元素置换掺杂β-SiC单晶块体体系[001]向拉伸变形行为,对体系的拉伸断裂微观机理和5×10⁸/s,1×10⁹/s,1×10¹⁰/s三种应变速率下的力学行为进行分析.发现当拉伸应变量达到某个临界值后,Si-C sp³,C-C sp³键会分别向Si-C sp²和C-C sp²弱键转化.形成一定量sp²键后,β-SiC内部出现孔洞并发生断裂.由于C-C sp³键比Si-C sp³键更易向sp²弱键转化,导致C元素掺杂会降低SiC的强度、弹性模量和拉伸断裂应变.此外还发现此三种应变速率不影响β-SiC的杨氏模量,但影响其拉伸强度.     

Silicon heterojunction solar cell with amorphous silicon oxide buffer and microcrystalline silicon oxide contact layers

This Letter reports on the fabrication and characterization of silicon heterojunction solar cells with silicon oxide based buffer (intrinsic amorphous silicon oxide) and contact layers (doped microcrystalline silicon oxide) on flat p‐type wafers. The critical dependency of the cell performance on the front and rear buffer layer thickness reveals a trade‐off between the open circuit voltage V_oc and the fill factor FF. At the optimum, the highest efficiency of 18.5% (active area = 0.67 cm²) was achieved with V_oc = 664 mV, short circuit current J_sc = 35.7 mA/cm² and FF = 78.0%. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Simulation and fabrication study of porous silicon photonic crystal

The present work reports design and fabrication of porous silicon based one-dimensional (1D) photonic crystal. Distributed Bragg reflector (DBR) is a 1D photonic crystal composed of multilayer stack of high and low refractive index layers. Design of porous silicon DBR is a complex one and requires appropriate control in optical parameters of its constituent layers. In order to design DBR, two porous silicon single layer samples were fabricated using current density of 10 and 50 mA/cm². Optical characterization of single layer samples showed series of interference fringes. Reflective interferometric Fourier transform spectroscopy (RIFTS) method was employed to determine optical constants of porous silicon single layers. DBR simulation was carried out based on transfer matrix method. DBR was then fabricated using optical parameters obtained from RIFTS method. Reflection bandwidth of prepared DBR was found to be 216 nm, which is comparable to the simulated value of 203 nm.     

Thin macroporous silicon heterojunction solar cells

We demonstrate the processing of a heterojunction solar cell from a purely macroporous silicon (MacPSi) absorber that is generated and separated from a monocrystalline n‐type Cz silicon wafer by means of electrochemical etching. The etching procedure results in straight pores with a diameter of (4.7 ± 0.2) µm and a distance of 8.3 µm. An intrinsic amorphous Si (a‐Si)/p⁺‐type a‐Si/indium tin oxide (ITO) layer stack is on the front side and an intrinsic a‐Si/n⁺‐type a‐Si/ITO layer stack is on the rear side. The pores are open when depositing the layers onto the 3.92 cm²‐sized cell. The conductive layers do not cause shunting through the pores. A silicon oxide layer passivates the pore walls. The energy‐conversion efficiency of the (33 ± 2) µm thick cell is 7.2%. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

21.0%‐efficient co‐diffused screen printed n‐type silicon solar cell with rear‐side boron emitter

Plasma enhanced chemical vapor deposition (PECVD) is applied to deposit boron silicate glasses (BSG) acting as boron diffusion source during the fabrication of n‐type silicon solar cells. We characterize the resulting boron‐diffused emitter after boron drive‐in from PECVD BSG by measuring the sheet resistances R_sheet,B and saturation current densities J_0,B. For process optimization, we vary the PECVD deposition parameters such as the gas flows of the precursor gases silane and diborane and the PECVD BSG layer thickness. We find an optimum gas flow ratio of SiH₄/B₂H₆= 8% and layer thickness of 40 nm. After boron drive in from these PECVD BSG diffusion sources, a low J_0,B values of 21 fA/cm² is reached for R_sheet,B = 70 Ω/□. The optimized PECVD BSG layers together with a co‐diffusion process are implemented into the fabrication process of passivated emitter and rear totally diffused (PERT) back junction (BJ) cells on n‐type silicon. An independently confirmed energy conversion efficiency of 21.0% is achieved on 15.6 × 15.6 cm² cell area with a simplified process flow. This is the highest efficiency reported for a co‐diffused n‐type PERT BJ cell using PECVD BSG as diffusion source. A loss analysis shows a small contribution of 0.13 mW/cm² of the boron diffusion to the recombination loss proving the high quality of this diffusion source. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Structural, optical and electrical properties of amorphous silicon thin films prepared by sputtering with different targets

Amorphous silicon (a-Si) films were prepared by sputtering method with polycrystalline and monocrystalline silicon targets. Structural, optical and electrical properties of the a-Si films have been systematically studied. The deposition power is from 100 to 200 W. Compared with the a-Si films deposited by using monocrystalline silicon target, the a-Si films prepared with polycrystalline silicon target exhibit better growth property, similar optical band gap, and own the highest mobility of 1.658 cm²/Vs, which make a good match with the optimal window of optical band gap for a-Si solar cells. The results indicated that the polycrystalline silicon target is superior to the monocrystalline silicon target when used to prepare a-Si films as the intrinsic layer in a-Si solar cells.     

X-ray diffraction studies of silicon implanted with high-energy erbium ions

Silicon crystals after implantation of erbium ions with energies in the range 0.8–2.0 MeV and doses in the range 1×10¹²–1×10¹⁴ cm⁻² have been studied by two-and three-crystal x-ray diffraction. Three types of two-crystal reflection curves are observed. They correspond to different structural states of the implanted layers. At moderate doses (1×10¹²–1×10¹³ cm⁻²) a positive strain is observed, due to the formation of secondary radiation defects of interstitial type. An increase of the implantation dose is accompanied by the formation of an amorphous layer separating the bulk layer and a thin monocrystalline surface layer. At an implantation dose of 1×10¹⁴ cm⁻² the monocrystalline surface layer is completely amorphized. Parameters of the implantation layers are determined. A model of the transformation of structural damage is discussed. Fiz. Tverd. Tela (St. Petersburg) 39, 853–857 (May 1997)     

低工作电压聚噻吩薄膜晶体管

以高掺杂Si单晶片作为衬底且充当栅电极,采用磁控溅射法在硅片上沉积HfTiO薄膜作为栅介质层,聚三己基噻吩(P3HT)薄膜作为半导体活性层,金属Au作为源、漏电极,并采用十八烷基三氯硅烷(OTS)对栅介质层表面修饰,在空气环境下成功地制备出聚合物薄膜晶体管(PTFT).PTFT器件测试结果表明,该晶体管在低的驱动电压(<-1 V)下仍呈现出良好的饱和行为,其阈值电压和有效场效应迁移率分别为0.4 V和2.2×10^-2 cm²/V ·s.通过对金属-聚合物-氧化物 关键词： 聚合物薄膜晶体管 聚三己基噻吩 场效应迁移率 k栅介质')" href="#">高k栅介质     

Synthesis and characterization of porous silicon layers for 1D photonic crystal application

In this paper, we studied the optical and physical properties of electrochemically prepared porous silicon layers. The atomic force microscopy analysis showed that the etching depth, pore diameter and surface roughness increase as the etching time increased from 30 to 50 mA/cm². By tuning two current densities J₁ = 50 mA/cm² and J₂ = 30 mA/cm², two samples of 1D porous silicon photonic crystals were fabricated. The layered structure of 1D photonic crystals has been confirmed by scanning electron microscopy measurement which showed white and black strips of two distinct refractive index layers. Finally, the measured reflectance spectra of 1D porous silicon photonic crystals were compared with simulated results.     

Reversible multi polyelectrolyte layers on gold nanoparticles

The fabrication of semiconducting functional layers using low-temperature processes is of high interest for flexible printable electronics applications. Here, the one-step deposition of semiconducting nanoparticles from the gas phase for an active layer within a thin-film transistor is described. Layers of semiconducting nanoparticles with a particle size between 10 and 25?nm were prepared by the use of a simple aerosol deposition system, excluding potentially unwanted technological procedures like substrate heating or the use of solvents. The nanoparticles were deposited directly onto standard thin-film transistor test devices, using thermally grown silicon oxide as gate dielectric. Proof-of-principle experiments were done deploying two different wide-band gap semiconducting oxides, tin oxide, SnO _x , and indium oxide, In₂O₃. The tin oxide spots prepared from the gas phase were too conducting to be used as channel material in thin-film transistors, most probably due to a high concentration of oxygen defects. Using indium oxide nanoparticles, thin-film transistor devices with significant field effect were obtained. Even though the electron mobility of the investigated devices was only in the range of 10^?6?cm^2?V^?1?s^?1, the operability of this method for the fabrication of transistors was demonstrated. With respect to the possibilities to control the particle size and layer morphology in situ during deposition, improvements are expected.     

Surface-enhanced Raman spectroscopy of hexabenzobenzene,C24H12, an analogue of a graphene nanostructure

While large scale fabrication of graphene nanoribbons remains a challenge, there exist materials which can be fabricated in quantities such as hexabenzobenzene,HBZB, (C₂₄H₁₂) and which have a two-dimensional (2D) carbon structure similar to graphene nanostructures. Using a 632 nm laser, no Raman spectra could be obtained from the solid material because of a strong luminescence produced by the laser. However, surface-enhanced Raman spectroscopy enabled the measurement of some of the Raman active modes. The G and D modes, which are characteristic fingerprints of a 2D graphene structure, were observed at 1331 and 1600 cm^?1, respectively. Density functional theory at the B3LYP/6-31G^* level was used to calculate the minimum energy structure and the Raman active vibrational frequencies of HBZB. The calculated minimum energy structure was 2D having D_6h symmetry in agreement with the experimental structure in the liquid phase. The calculated frequencies were in good agreement with the measured values.