BF_2~+注入硅分子效应的椭偏谱多层分析

把离子注入层设想成由50多层的微分薄层构成,用以研究BF_2~+的分子效应。我们在1.6—5.0eV光子能量范围内,测量了不同剂量也(3×10~(13)-5×10~(15)ion/cm~2),147keV BF_2~+分子离子77K注入硅以及相应的B~+、F~+注入硅样品的椭偏谱。由实验测得的离子注入样品的椭偏光谱、多层薄膜光学模型、有效介质近似理论(EMA)和计算软件,可分析离子注入硅的损伤分布、表面自然氧化物的非均匀性和界面组份。其分析结果与背散射沟道技术和透射电子显微镜的测定结果相一致。研究中发现,低温BF~2~+注入的损伤层和非晶层都首先在样品表面形成,与B~+、F~+注入损伤相比,BF_2~+注入存在显著的分子效应。     

利用光丝诱导荧光光谱测量单质碘升华过程

利用飞秒激光大气成丝高强激光诱导荧光非线性光谱对碘单质升华过程进行了研究。研究结果发现飞秒光丝可诱导升华到空气中的碘分子产生清晰特征荧光谱。通过监测碘分子在341.6nm(D→X~1Σ_g~+跃迁)处的荧光谱线,利用时间分辨测量方法观察到碘分子荧光强度随着加热温度以及测量位置与固态碘样品距离的变化而明显变化,展示了光丝诱导荧光光谱技术应用于物态变化规律探索的可行性。     

离子注入法Mn掺杂InAs/GaAs量子点的光磁性质

用离子注入法对InAs/GaAs量子点掺杂Mn离子,量子点样品经过快速退火处理后同时具有低温铁磁性和发光性能.注Mn量子点发光峰在退火后蓝移,在较高注入剂量的样品中这种由于互扩散带来的蓝移受到抑制,认为这与样品中的缺陷以及Mn聚集在量子点周围减小量子点所受的应力,同时形成的团簇阻碍了界面上原子的互扩散作用有关.Mn在盖层中形成了GaMnAs和小的Mn颗粒,表现出较好的低温铁磁性.     

离子注入法Mn掺杂InAs/GaAs量子点的光磁性质

用离子注入法对InAs/GaAs量子点掺杂Mn离子,量子点样品经过快速退火处理后同时具有低温铁磁性和发光性能.注Mn量子点发光峰在退火后蓝移,在较高注入剂量的样品中这种由于互扩散带来的蓝移受到抑制,认为这与样品中的缺陷以及Mn聚集在量子点周围减小量子点所受的应力,同时形成的团簇阻碍了界面上原子的互扩散作用有关.Mn在盖层中形成了GaMnAs和小的Mn颗粒,表现出较好的低温铁磁性.     

无酸水热法制备多孔硅及其PⅢ表面改性

采用无酸水热法,制备了多孔硅材料.使用扫描电子显微镜、原子力显微镜等手段观察了样品表面形貌,比较了在不同氧化铋刻蚀剂量下得到的多孔硅结构,发现随着刻蚀剂浓度的增加,平均孔径尺寸变大,且孔径分布趋于离散.使用等离子浸没注入技术,对多孔硅样品进行了表面注氮处理.室温荧光光谱研究发现处理后的样品的光谱峰位产生了蓝移,根据X光电子能谱仪检测的结果发现样品表面形成了Si-NxOy相,这一物相的出现导致了光谱的蓝移.     

氢离子注入法提高InAsP/InP应变多量子阱发光特性

采用气态源分子束外延系统生长了InAsP/InP应变多量子阱,研究了H 注入对量子阱光致发光谱的影响以及高温快速退火对离子注入后的量子阱发光谱的影响.发现采用较低H 注入能量(剂量)时,量子阱发光强度得到增强;随着H 注入能量(剂量)的增大,量子阱发光强度随之减小.H 注入过程中,部分隧穿H 会湮灭掉量子阱结构界面缺陷,同时H 也会对量子阱结构带来损伤,两者的竞争影响量子阱发光强度的变化.高温快速退火处理后,离子注入后的量子阱样品发光峰位在低温10K相对于未注入样品发生蓝移,蓝移量随着H 注入能量或剂量的增大而增加.退火过程中缺陷扩散以及缺陷扩散导致的阱层和垒层之间不同元素互混是量子阱发光峰位蓝移的原因.     

由浅离子注入实现的MQW混合

用浅Ｐ＾＋离子注入ＩｎＧａＡｓ／ＩｎＧａＡｓＰ应变多量子阱（ＭＱＷ）激光器Ｈ２／Ｎ２混合气氛下的快速退火,体内ＭＱＷ层发生组份混合（ｉｎｔｅｒｍｉｘｉｎｇ）,导致器件的带隙波长蓝移（ｂｌｕｅ ｓｈｉｆｔ）,结构的光荧光（ＰＬ）峰值波长向短波方向移动了７６ｎｍ。作者认为,有源区中的应力对量子阱混合起到了十分关键性的作用。     

硅晶体中离子注入应力的红外光弹性测量及研究

根据光弹性原理,利用红外光弹性测量系统,采用Senarmont补偿法,对离子注入工艺应力进行了测量。对离子注入工艺应力、退火后应力、应力的分布、应力随剂量和表面浓度的变化进行了研究。     

一种新型自聚集诱导发光材料的研究

为了研究一种新型的聚集诱导发光材料(1-绕丹宁-芘),采用荧光光谱测量法和ORIGIN软件对样品进行了实验验证和理论分析,发现其具有一些新颖的光学性质。结果表明,在稀释溶液浓度时,样品的发射峰出现大幅蓝移;在升高温度时,样品出现了荧光增强现象。这些性质不同于常见的聚集诱导发光材料,与1-绕丹宁-芘在溶液中聚集时生成超分子结构有关。该研究在生物成像、医学领域、传感器、探测器及有机显示方面有一定的应用前景,对有机发光材料的研究有重要的意义。     

磷离子注入诱导InGaAsP／InP双量子阱混合的研究

本文用光荧光(PL)方法研究了磷离子注入具有两个不同发射波长的InGaAsP/InP双量子阱结构引起的混合。注入能量为120keV,剂量范围为1×1011-1×1014/cm2。注入后,在高纯氮保护下,样品在700℃进行快速热退火30秒。实验结果表明,小剂量注入(～1011/cm2)能较好地诱导近表面阱的混合,且两个阱保持了不同发射波长,说明离子注入诱导量子阱混合与注入深度有关。大剂量注入(>1012/cm2)时,发射波长为1.59μm量子阱混合的程度(蓝移值大于130nm)超过了1.52μm量子阱混合的程度,且两个阱的PL发射峰基本上合并成一个单峰。     

P型张应变Si/SiGe量子阱红外探测器的能带设计

提出P型张应变Si/SiGe量子阱红外探测器(QWIP)结构,应用k·P方法计算应变Si/SiGe量子阱价带能带结构和应变SiGe合金空穴有效质量.结果表明量子阱中引入张应变使轻重空穴反转,基态为有效质量较小的轻空穴态,因此P型张应变Si/SiGe QWIP与n型QWIP相比具有更低的暗电流;而与P型压应变或无应变QWIP相比光吸收和载流子输运特性具有较好改善.在此基础上讨论了束缚态到准束缚态子带跃迁型张应变p-Si/SiGe QWIP的优化设计.     

不同直径张应变锗材料对光谱和晶体质量的影响

绝缘体上张应变锗材料是通过能带工程提高锗材料光电性能得到的一种新型半导体材料,在微电子和光电子领域具有重要的应用前景.采用微电子技术中的图形加工方法以及利用锗浓缩的技术原理,在绝缘体上硅(SOI)材料上制备了绝缘体上张应变锗材料.喇曼与室温光致发光(PL)测试结果表明,不同圆形半径的绝缘体上锗材料张应变均为0.54％.对于绝缘体上张应变锗材料,应变使其发光红移的效果强于量子阱使其发生蓝移的效果,总体将使绝缘体上张应变锗材料的直接带发光峰位红移.同时0.54％张应变锗材料的直接带发光强度随着圆形半径的增大而减弱,这主要是因为圆形半径大的样品其晶体质量较差.该材料可进一步用于制备锗微电子和光电子器件.     

Strain-induced modifications of the band structure ofInxGa1-xP-In0.5Al0.5Pmultiple quantum wells

The effect of strain on the band structure of In_xGa_1-xP-In_0.5Al_0.5P multiple quantum wells (MQW's) has been investigated from high-pressure and low-temperature photoluminescence measurements. The biaxial strain in the wells was varied between +0.6% compressive to -0.85% tensile strain by changing the well composition x from 0.57 to 0.37. Strain increases the valence band offsets in either tensile or compressively strained structures. Whereas relatively insensitive to tensile strain, the valence band offsets showed a strong dependence on the magnitude of the compressive strain. Good agreement is found between the measured valence band offsets and those predicted by the model solid theory, except for the largest compressively strained MQW's, for which the model calculations underestimate the measured valence band offset. Strain and the associated variations in composition also modified the separation among the well states associated with Γ_1c, L_1c , and X_1c. From these results, the bandgaps of each conduction band extrema were calculated in In_xGa_1-xP for 0.37相似文献   

Photoluminescence characterization of AlGaN-GaN pseudomorphic quantum wells and calculation of strain induced bandgap shifts

The low temperature (77 K) photoluminescence characteristics of Al _x Ga_1-x N-GaN strained layer quantum wells with differentx values grown by metalorganic chemical vapor deposition (MOCVD) were investigated. The photoluminescence spectra were useful in analyzing both quantum confinement effects and strain induced energy shifts. The strain induced shifts were found to be a strong function of aluminum compositionx. A model was developed to calculate the strain induced bandgap shifts atk = 0. The values predicted by this model which took into account the wurtzite crystal structure of the material system, were in good agreement with (i.e. within 2 meV of) the experimentally measured shifts.     

Effects of boron incorporation on the strain and photoluminescence properties of GaAsSb/GaAs quantum wells

Boron-containing GaAsSb/GaAs quantum wells (QWs) with different antimony (Sb) mole fractions were grown by low-pressure metal–organic chemical vapor deposition for the first time. The effects of boron incorporation on the performance of GaAsSb/GaAs QWs are discussed. For samples with low compressive strain, injection of triethylboron can enhance the Sb content and increase the compressive strain, although boron incorporation can lead to a reduction in strain. This effect was less for strained GaAsSb/GaAs QWs, so the compressive strain of these QWs did not vary. Room-temperature photoluminescence emission at 1116 nm with a full-width at half-maximum (FWHM) value of 56 meV was obtained for strained BGaAsSb/GaAs QWs.     

Pure strain effect on differential gain of strained InGaAsP/InPquantum-well lasers

The effect of pure strain on the differential gain of strained InGaAsP/InP quantum-well lasers (QWLs) is analyzed on the basis of the valence band structures calculated by k×p theory. By using an InGaAsP quaternary compound as an active layer, it becomes possible to study the relationship between the differential gain and strain (both tensile and compressive) when both the quantum-well thickness and the emission wavelength are kept constant. It is shown that the tensile strain not only reduces the density of states in the valence band but also increases the energy spacings between the first two valence subbands. It is concluded that tensile strain has a more pronounced impact on the improvement of differential gain in InP-based, strained QWLs as compared with compressive strain     

Polarization dependence of photo-detection in strained multiplequantum-well semiconductor lasers

We investigated polarization dependence of photo-detection in strained layer multiple quantum-well (SL-MQW) lasers for time compressive multiplex (TCM) application. The polarization dependence of SL-MQW lasers is larger than that of bulk lasers because of the quantum effect. To improve the polarization dependence of photo-detection, we theoretically and experimentally analyzed the effect of strain quantity on the polarization dependence, and found that large tensile strained quantum-well structure is suitable for the small polarization independence of 0.8 dB and low threshold current characteristics. Moreover, we achieved smaller polarization dependence less than 0.5 dB by applying reverse bias voltage in the photo-detection mode     

双轴应变对纤锌矿GaN、AlN、InN及其合金电子有效质量的影响(英文)

利用第一性原理计算方法密度泛函理论的局域密度近似计算了纤锌矿氮化铝(AlN)、氮化镓(GaN)、氮化铟(InN)及其合金在双轴应变下的电子有效质量。对于GaN和AlN,张应变使电子有效质量增大而压应变使电子有效质量减少,但却使InN电子有效质量在张应变和压应变下都增大。由于三元合金(AlxGa1-xN,InxGa1-xN和AlxIn1-xN)与GaN异质结的新颖特性,同时计算了三元合金在松弛和应变下电子有效质量的变化趋势。受制于GaN基板的平面应力,外延AlxGa1-xN和AlxIn1-xN电子有效质量将减少,而InxGa1-xN电子有效质量增大,且随着In含量变大而更显著。对铟氮化合物应变下电子有效质量异常的机制也做了讨论。     

Influence of External Strain on the Growth of Interfacial Intermetallic Compounds Between Sn and Cu Substrates

This study used a four-point bending procedure to investigate the influence of compressive and tensile strain on the growth of an interfacial Cu-Sn intermetallic compound (IMC) layer. The test specimens were prepared by depositing 25?μm layers of matte or bright tin atop a copper substrate using electroplating. Samples were then placed in a furnace at 200°C, and external bending strain was applied through a strained substrate. Comparisons were made between samples undergoing tensile strain or compressive strain, and those without strain. We observed the influence of strain levels and aging time on the formation of the IMC. Both tensile and compressive strain influenced the formation of the Cu/Sn IMC. In matte tin samples, the IMC thickness increased under compressive strain and decreased under tensile strain. In contrast, in bright tin samples, the IMC thickness increased under both compressive and tensile strained substrate conditions. The growth rate of IMC was faster in strained bright tin samples than in strained matte tin samples. Moreover, the formation of IMC microscopic structures under external strain differed considerably according to the source of tin.     

Field screening in (111)B InAsP/lnP strained quantum wells

Low-temperature photoluminescence measurements were performed on InAsP/InP strained quantum wells grown on InP (lll)B substrates by gas-source molecular beam epitaxy. The emission energy was observed to increase as the pump-power density increased. This was attributed to the screening of the internal piezoelectric field by photo-generated carriers. The energy shift was as large as 35 meV for an InAs_0.28P_0.72/InP quantum well with a lattice mismatch of ~0.9%. A similar structure with a smaller strain showed saturation of the energy shift with increasing pump-power density. We performed a model calculation which includes the quantum confined Stark effect, and this saturation was correlated with a flat-band structure of the quantum well due to the nearly complete screening of the built-in electric field.