波状PIN电光调制结构

PIN是电光调制器中常见的一种调制结构,该结构工作时产生的热光效应直接影响着电光调制器的性能。为了缓解这种热光效应对调制器的影响,从PIN调制原理出发,在绝缘体上硅薄膜(SOI)材料的基础上提出了一种波状PIN调制结构,并将该结构与普通PIN调制结构进行对比,定量分析了波状PIN结构对温度、折射率以及调制区载流子浓度的影响,通过仿真得出2V调制电压下,波状PIN结构的温度降低了11.6%,抑制热光效应使得折射率漂移减小了28%,调制区注入载流子浓度提高了26.7%。通过实验,分别制作了波状PIN结构和普通PIN结构的微环电光调制器,经过测试发现波状PIN结构具有更大的谐振峰蓝移值,该结构有效抑制了热光效应的影响,证明了该新型结构的优越性及理论分析的正确性。     

ZnO/Si异质结的光电转换特性研究

利用直流反应溅射方法在p型Si衬底上生长掺Al的n型ZnO薄膜,测量了由n型ZnO薄膜和p型Si衬底组成的异质结在黑暗和光照条件下的I-V特性,结果表明该异质结具有优良的整流特性,而且在光照条件下的反向电流迅速增大并很快趋于饱和.通过测量ZnO薄膜的光电流和异质结的光电压的光谱响应,初步分析了异质结的光电转换机理.测量结果显示,在入射光波长为380nm时光电流强度明显下降,反映出光电流与ZnO薄膜禁带宽度的密切关系;同时还发现,在与ZnO禁带宽度相对应的波长前后所产生的光生电压方向相反.推测这一现象与异质结的能带结构密切相关. 关键词： ZnO薄膜 异质结 光电转换 光谱响应     

a-C: Fe/AlOx/Si基异质结的光伏效应

使用脉冲激光沉积(PLD)依次沉积氧化铝和碳膜制备了a-C: Fe/AlO_x/Si基异质结,研究了其光伏效应及其在太阳能电池上的应用.该太阳能电池在标准日光照射(AM1.5,100 mW/cm²)下,可获得0.33 V的开路电压和4.5 mA/cm²的电流密度,太阳能电池的转换效率为0.35%.通过C-V测量,证明了氧化铝层的引入降低了界面能级数目,增加了界面势垒高度.界面能级数目降低减少了光生载流子在界面复合的 关键词： 光伏效应 非晶碳膜 异质结 氧化铝     

分子束外延生长Si/GaP(111)异质结的界面特性

本文研究了分子束外延(MBE)生长的n-N型Si/GaP(111)异质结的界面特性。采用C-V法测量Si/GaP(111)异质结的表观载流子浓度分布n(x),从中导出了异质界面的导带失配值和界面电荷密度。实验结果表明,n-N型Si/GaP(111)是一种弱整流结构。导带失配△E_c=0.10eV,界面电荷密度σ_i=8.8×10¹⁰cm^-2。通过表现载流子浓度n(x)的理论计算曲线与实验曲线符合较好,说明了实验结果的可靠性 关键词：     

分子束外延生长Si/GaP珐()异质结的界面特性

本文研究了分子束外延(MBE)生长的n-N型Si/GaP(Ⅲ)异质结的界面特性。采用C-V法测量Si/GaP(Ⅲ)异质结的表观载流子浓度分布n(x),从中导出了异质界面的导带失配值和界面电荷密度。实验结果表明,n-N型Si/GaP(Ⅲ)是一种弱整流结构。导带失配△E_c=0.10eV,界面电荷密度σ_i=8.8×10~(10)cm~(-2)。通过表现载流子浓度n(x)的理论计算曲线与实验曲线符合较好,说明了实验结果的可靠性。     

非对称氧掺杂对石墨烯/二硒化钼异质结肖特基势垒的调控

在纳米逻辑器件中,制造低的肖特基势垒仍然是一个巨大的挑战.本文采用密度泛函理论研究了非对称氧掺杂对石墨烯/二硒化钼异质结的结构稳定性和电学性质的影响.结果表明石墨烯与二硒化钼形成了稳定的范德瓦耳斯异质结,同时保留了各自的电学特性,并且形成了0.558 eV的n型肖特基势垒.此外,能带和态密度数据表明非对称氧掺杂可以调控石墨烯/二硒化钼异质结的肖特基接触类型和势垒高度.当氧掺杂在界面内和界面外时,随着掺杂浓度的增大,肖特基势垒高度都逐渐降低.特别地,当氧掺杂在界面外时, n型肖特基势垒高度可以降低到0.112 eV,提高了电子的注入效率.当氧掺杂在界面内时, n型肖特基接触转变为欧姆接触.平面平均电荷密度差分显示随着掺杂浓度的增大,界面电荷转移数量逐渐增多,导致费米能级向二硒化钼导带底移动,证实了随着氧掺杂浓度增大肖特基势垒逐渐降低,并由n型肖特基向欧姆接触的转变.研究结果将对基于石墨烯的范德瓦耳斯异质结肖特基势垒调控提供理论指导.     

PLD法生长n-Zn1-xCoxO/p-Si异质结的电学性能研究

用高功率脉冲激光轰击Zn1-xCoxO,得到锌、钴和氧的原子、分子和团簇等混合体,并在p型单晶Si表面反应生成n型Zn1-xCoxO.X射线衍射(XRD)、原子力显微镜(AFM)研究表明,这层材料是结构致密均匀、呈c轴高度择优取向的薄膜,与p型Si材料形成n-Zn1-xCoxO/p-Si异质结.在Zn1-xCoxO中加入H,生成了Co-H-Co聚合体,异质结的势垒高度随着Co含量的增加而增加,同时深能级的Co-d轨道捕获作为浅施主的间隙H提供的电子,造成的体系n型半导体层的载流子浓度降低,电阻率提高,使得n-Zn1-xCoxO/p-Si异质结在6.5V时漏电流降致6×10-3 mA,反向击穿电压超过20V,电学性能得到显著改进.     

固体C60/Si异质结的电学表征——整流特性、能带模型与温偏效应

研究了非掺杂固体C₆₀与n-Si和与p-Si接触的电学性质,电流-电压(J-V)特性测量表明两种接触的导电极性相反,且都具有很强的整流作用,表明在两种接触界面附近存在着阻挡载流子输运的、性质不同的势垒.电流-温度(J-T)测量表明,电流与温度的倒数呈指数依赖关系,从中估算出C₆₀/n-Si和C₆₀/p-Si异质结的有效势垒高度分别为0.30和0.48eV.引进异质结的能带模型,成功地解释了上述测量结果,由能带模型和测量数据估算出以硅为衬底的 关键词：     

碲镉汞异质结能带结构的优化设计

分别对带隙较宽(较窄)的p型材料在带隙较窄(较宽)的n型材料之上的碲镉汞(MCT)异质结的能带结构进行了理论分析.在应用的理论模型中提出了一个简单的载流子浓度近似模型用于计入载流子简并效应和导带非抛物线性，同时还考虑到了价带失配的影响.就p-n结位置(z_B)和界面电荷密度(Q)两个参数对MCT异质结能带结构的影响进行了系统分析，发现这些影响是不可忽略的.根据这些影响特征，进一步得出了z_B和Q参数之间的优化设计规律. 关键词： 碲镉汞(MCT) 异质结 载流子浓度近似     

双异质结结构的双极型有机薄膜晶体管的研制

制备了基于F₁₆CuPc和CuPc的双异质结结构的双极型有机薄膜晶体管。该器件的载流子迁移率是相同工艺制备的F₁₆CuPc和CuPc双层单异质结有机薄膜晶体管器件的4~5倍。同时,该双异质结结构还能调整载流子的阈值电压,减少双层结构对薄膜厚度等工艺条件的苛刻要求。这种双异质结结构为提升双极型有机薄膜晶体管器件的性能提供了一种有效方法。     

一种新型SOI结构——SiGe-OI材料研究进展

SOI(silicononinsulator ,绝缘层上的硅 )技术和SiGe(silicongermanium ,锗硅 )技术都是微电子领域的前沿技术 .SiGe-OI(SiGe -on -insulator ,绝缘层上的锗硅 )新型材料是最近几年来才出现的一种新型SOI材料 ,它同时具备了SOI技术和SiGe技术的优势 ,因而成为当前微电子研究领域的最前沿课题之一 .文章结合中国科学院上海微系统与信息技术研究所的工作 ,综述了SiGe-OI材料研究情况和应用前景 ,详细介绍了其主要的制备方法 ,最后报道了作者在SiGe -OI材料研究上的一些实验结果 .     

Condensation of excitons and the spectrum of multiparticle states in SiGe/Si quantum wells: The role of the barrier in the conduction band

It has been demonstrated that the barrier in the conduction band represented by the SiGe layer in SiGe/Si quantum wells affects the work function and equilibrium density of the quasi-two-dimensional condensed phase formed in these structures. The existence of a new recombination channel with unconventional characteristics is uncovered in the structures with barrier heights close to the critical value for the formation of the electron-hole liquid.     

量子阱Si/SiGe/Sip型场效应管阈值电压和沟道空穴面密度模型

Si材料中较低的空穴迁移率限制了Si互补金属氧化物半导体器 件在高频领域的应用. 针对SiGe p型金属氧化物半导体场效应管(PMOSFET)结构, 通过求解纵向一维泊松方程,得到了器件的纵向电势分布, 并在此基础上建立了器件的阈值电压模型,讨论了Ge组分、缓冲层厚度、 Si帽层厚度和衬底掺杂对阈值电压的影响.由于SiGe沟道层较薄, 计算中考虑了该层价带势阱中的量子化效应. 当栅电压绝对值过大时, 由于能带弯曲和能级分裂造成SiGe沟道层中的空穴会越过势垒到达Si/SiO₂界面, 从而引起器件性能的退化. 建立了量子阱SiGe PMOSFET沟道层的空穴面密度模型, 提出了最大工作栅电压的概念, 对由栅电压引起的沟道饱和进行了计算和分析. 研究结果表明,器件的阈值电压和最大工作栅压与SiGe层Ge组分关系密切, Ge组分的适当提高可以使器件工作栅电压范围有效增大.     

The hole transport characteristics in SiGe/Si double and triple barrier resonant tunneling structures

Experimental measurements and theoretical calculations have been used to study the hole transport characteristics in SiGe/Si double and triple barrier resonant tunneling structures. The main emphasis is put on discussing the symmetry of I–V characteristics with forward and reverse bias, their temperature dependences and relations to quantum well designs. The calculations show that at current resonance, the sub-level can be much lower (e.g, for heavy hole resonance) or much higher (e.g, for light hole resonance) than the quasi-Fermi-level in the spacer. The distinctly different features of the measured first and second resonances for SiGe/Si double and triple barrier resonant tunneling, can be understood, by considering the different population of the heavy hole and light hole bands in the spacer region and the temperature dependences of Fermi-level, carrier mobility and effective masses. The analysis of dependences of the transmission and I–V curve with quantum well designs presents the possibility of using an asymmetric triple barrier structure to improve the resonant tunneling performance.     

Material requirements and design considerations for Si/SiGe heterojunction CMOS

Five vertical architecture options for SiGe/Si heterojunction CMOS devices are compared using technology computer-aided design. The benefit of using SiGe over conventional MOSFETs is set to increase for future technology generations. We investigate the impact of material degradation, to determine the minimum requirements needed for HMOS to offer real advantages over conventional CMOS.     

应变SiGe SOI量子阱沟道PMOSFET阈值电压模型研究

在绝缘层附着硅(SOI)结构的Si膜上生长SiGe合金制作具有SiGe量子阱沟道的SOI p型金属氧化物半导体场效应晶体管(PMOSFET)，该器件不仅具有SOI结构的优点，而且因量子阱中载流子迁移率高，所以进一步提高了器件的性能.在分析常规的Si SOI MOSFET基础上，建立了应变SiGe SOI 量子阱沟道PMOSFET的阈值电压模型和电流-电压(I-V)特性模型，利用Matlab对该结构器件的I-V特性、跨导及漏导特性进行了模拟分析，且与常规结构的器件作了对比.模拟结果表明，应变SiGe SOI量子阱沟道PMOSFET的性能均比常规结构的器件有大幅度提高. 关键词： 应变SiGe SOI MOSFET 阈值电压 模型     

单Halo全耗尽应变Si 绝缘硅金属氧化物半导体场效应管的阈值电压解析模型

为了改善金属氧化物半导体场效应管(MOSFET) 的短沟道效应(SCE)、 漏致势垒降低(DIBL) 效应, 提高电流的驱动能力, 提出了单Halo 全耗尽应变硅绝缘体 (SOI) MOSFET 结构, 该结构结合了应变Si, 峰值掺杂Halo结构, SOI 三者的优点. 通过求解二维泊松方程, 建立了全耗尽器件表面势和阈值电压的解析模型. 模型中分析了弛豫层中的Ge组分对表面势、表面场强和阈值电压的影响, 不同漏电压对表面势的影响, Halo 掺杂对阈值电压和DIBL的影响.结果表明, 该新结构能够抑制SCE和DIBL效应, 提高载流子的输运效率. 关键词： 应变Si 阈值电压 短沟道效应 漏致势垒降低     

-Factor tuning of 2D electrons in double-gated Si/SiGe quantum wells

We report on the design and first experiments of Si/SiGe heterostructures that allow gate-operated shifting of a 2D electron gas between two channels with different Landé g-factors. This allows gate-operated moving of electrons in and out of resonance in an electron spin resonance (ESR) experiment, which can act as a building block of a proposed solid-state quantum computer. We use MBE-grown modulation-doped quantum-wells (QWs) on SiGe pseudosubstrates with up to 30% Ge and low-temperature electron mobilities up to . A double QW structure with two different Ge contents separated by a thin barrier was optimized for this purpose with self-consistent simulations. The band structure simulations show that by applying gate voltages one can completely shift the wave function from one well to the other. First experiments on pure Si channels show the working of the gate setup. Both carrier density and mobility can be increased by using the back gate which corresponds to shifting the wave function in the channel.     

Luminescence of a quasi-two-dimensional electron-hole liquid and excitonic molecules in Si/SiGe/Si heterostructures upon two-electron transitions

The low-temperature photoluminescence of Si/Si_0.91Ge_0.09/Si heterostructures in the near-infrared and visible spectral ranges is investigated. For the structure in which the barrier in the conduction band formed by the SiGe layer is transparent to electron tunneling, the broad luminescence line observed in the visible range is analyzed by comparing its shape with the numerical convolution of the spectrum of near-infrared recombination radiation originating from the electron-hole liquid. The comparison demonstrates that, at high excitation levels, the visible-range emission is caused by two-electron transitions in a quasi-two-dimensional spatially direct electron-hole liquid. Furthermore, the combined analysis of the photoluminescence spectra in the near-infrared and visible ranges yields the binding energy of a quasi-two-dimensional free biexciton in the SiGe layer of these heterostructures. In the structures with a wide SiGe layer that is not tunneling-transparent to electrons, a spatially indirect (dipolar) electron-hole liquid is observed.     

Electric subbands in Si/SiGe strained layer superlattices

The subband structure for electrons in Si/SiGe strained layer superlattices along the (100) direction is calculated self-consistently including many-body effects in the local density approximation. The strain induced splitting of the six-fold degenerate conduction band results in different potential wells for different valleys. The charge distribution between the layers and valleys is calculated versus carrier concentration and conduction band offset for different strains. An estimate for the band offsets is obtained by comparison of experimental results with the calculations.