Photoluminescence Characteristics of InAs Self-assembled Quantum Dots in InGaAs/GaAs Quantum Well

在InGaAs/GaAs量子阱中生长了两组InAs量子点样品,用扫描电子显微镜(SEM)测量发现,量子点呈棱状结构,而不是通常的金字塔结构,这是由多层结构的应力传递及InGaAs应变层的各向异性引起的。采用变温光致发光谱(TDPL)和时间分辨谱(TRPL)研究了其光致发光稳态和瞬态特性。研究发现,InGaAs量子阱层可以有效地缓冲InAs量子点中的应变,提高量子点的生长质量,可以在室温下探测到较强的发光峰。在量子阱中生长量子点可以获得室温下1 318 nm的发光,并且使其PL谱的半高宽减小到25 meV。Two types of InAs quantum dots grown in InGaAs/GaAs quantum well(DWELL) were fully investigated by time-resolved(TR) and temperature dependent photoluminescence(TDPL).Scanning electron microscopy(SEM) measurements show that the shape of quantum dots is prismatic,but not the common pyramid shape.We consider that it is attributed to stress transition of multi-layer structure and anisotropy of InGaAs strained layer.DWELL structures could combine both the effects of InGaAs buffer layer and cap layer and even effectively release the stress between the buffer layer and the QDs, which may greatly improve the QDs quality.Strong PL signal emitting at 1 318 nm can be detected at room temperature and the full width at half maximum of PL spectrum is only 25 meV at some temperature.浙江省舟山市科技项目(06110);; 浙江海洋学院人才引进项目(211050041

A New Type of Electromodulation Spectroscopy and Its Application

提出一种微接触电调制反射谱(LCER)测试方法,该方示与无接触电调制反射(CER)谱相比较,可极大降低调制电压。给出了自制的详细样品架结构,测量了InGaAs/GaAs量子阱样品,并与光调制反射谱(PR)相比较,结果证实了此方法的可行性和高光谱灵敏度,表明样品与电极的轻微接触既对测量结果没有明显的影响,又可简化测试条件,降低对测量环境的要求,是研究半导体材料和微结构一种方便而又有效的方法

Photoluminescence Spectroscopy Studies of InGaAsN Quantum Wells

我们测量了低N组分的InGaAsN/InGaAs/GaAs量子阱材料的光致发光(PL)谱,测量温度范围从13K到300K。实验结果显示,InGaAsN的PL谱的主峰值的能量位置随温度的变化呈现出反常的S型温度依赖关系。用Varshni经验公式对实验数据进行拟合之后,发现在低温下InGaAsN量子阱中的载流子是处于局域态的。此外,我们还测量了样品在不同的温度、不同的能量位置的瞬态谱,结果进一步证实了:在低温下,InGaAsN的PL谱谱峰主要是局域态激子的复合发光占据主导地位,而且InGaAsN中的载流子局域态主要是由N等电子缺陷造成的涨落势引起的。The photoluminescence (PL) spectroscopy in InGaAsN/InGaAs/GaAs quantum wells (QWs) with low-nitrogen composition has been measured in the temperature range 13-300K. The peak position energies of InGaAsN as measured by PL exhibit anomalous inverted S-shape-like temperature dependence. Fitting with Varshni empirical relation to PL data, we have found that carriers in InGaAsN QWs are localized at low temperatures. Moreover, Time-resolved photoluminescence (TRPL) measurements, performed for various temperatures and different PL energy position, further proved that the broad PL emission of InGaAsN at low temperature is mainly dominated by strong localization, which arises from nitrogen-induced fluctuating potential in quantum wells

InGaAs/GaAs应变量子阱的低温光伏谱

用光伏谱方法研究了IngAAS/gAAS应变量子阱结构中各子能级间的光跃迁，并与理论计算的结果进行了比较.分析了光伏谱峰能量随阱宽与温度的变化，并讨论了光伏谱峰强度的温度关系.国家自然科学资金;福建省自然科学基

Development of high-sensitivity preamplifier of surface photovoltaic spectroscopy

表面光伏技术可测量半导体材料的少数载流子的扩散长度、表面电荷等,能表征半导体微结构。采用静电计管作为信号的前置放大器具有电压增益低、体积大等缺点。介绍了一种表面光伏谱前置放大器的设计原理、设计方案和应用实例。该前置放大器具有灵敏度高、响应时间短、截止频率低等优点,并且体积小、使用成本低。The paper introduces the design and application of a new kind of surface photovoltaic spectroscopy preamplifier.This preamplifier has not only advantages of high sensitivity,low response time,low cut-off frequency,but also smaller size and lower price.厦门大学科技创新项目(Xdkjcx20061028)专利号(ZL00620156385.1

Effect of RF power on the structure and properties of ZnO∶Al films deposited by magnetron sputtering

采用RF磁控溅射技术以ZnO:Al2O3(2 wt%Al2O3)为靶材在石英玻璃衬底上制备多晶ZnO:Al(AZO)薄膜,通过XRD、AFM、AES以及Hall效应、透射光谱、折射率等手段研究了RF溅射功率(50~300 W)对薄膜的组织结构和电学,光学性能的影响。分析表明:所制备的AZO薄膜具有c轴择优取向,并且通过对不同功率下薄膜载流子浓度与迁移率的研究发现对于室温下沉积的AZO薄膜,晶粒间界中的O原子吸附是影响薄膜电学性能的主要因素。同时发现当功率为250 W时薄膜的电阻率降至最低(3.995×10-3Ω.cm),可见光区平均透射率为91%。Aluminum doped zinc oxide films are deposited by magnetron sputtering using a zinc oxide target doped with Al2O3(2 wt%.) with different RF powers on quartz substrate.The structural and compositional characteristics of the films are investigated by XRD,AFM,SEM,AES and XPS.respctively,while the electrical and optical properties of the thin films are studied by the Hall measurement and spectrophotometry,respectively.It has been found that all films deposited are c-axis preferred orientation perpendicular to the substrate with porous crystalline structure.The lowest resistivity obtained in this study is 3.9×10-3 Ω·cm for the film deposited at 250 W,and the average transmittance is 91% in the visible range.By comparing the samples deposited at various RF power,the oxygen absorption in the grain boundaries is the dominant factor which influences the electrical property of the AZO thin film

Structural,Electrical,and Optical Properties of Transparent Conductive Al-Doped ZnO Films Prepared by RF Magnetron Sputtering

室温下采用RF磁控溅射技术在石英衬底上制备了多晶ZnO:Al(AZO)透明导电薄膜,通过XRD,AFM,AES,Hall效应及透射光谱等测试研究了RF溅射功率、氩气压强对薄膜的结构、电学和光学性能的影响.分析表明:在最优条件下(溅射功率为250W,氩气压强为1.2Pa时),180nmAZO薄膜的电阻率为2.68×10-3Ω.cm,可见光区平均透射率为90%,适合作为发光二极管和太阳能电池的透明电极.所制备的AZO薄膜具有c轴择优取向,晶粒间界中的O原子吸附是限制薄膜电学性能的主要因素.Highly conductive transparent Al-doped zinc oxide(AZO)films with highly(002)-preferred orientation were successfully deposited on glass substrates at room temperature by RF magnetron sputtering.Optimization of deposition parameters was based on sputtering RF power and Ar pressure in the vacuum chamber.AZO films of 180nm with an electrical resistivity as low as 2.68×10-3 Ω·cm and an average optical transmission of 90% in the visible range were obtained at RF power of 250W and Ar pressure of 1.2Pa.The effect of chemisorption of oxygen on the grain boundary would capture electrons from conduction band and lead the formation of potential barriers among the crystallites,which will influence the electric property of the AZO thin films.The films have satisfactory properties of low resistance and high transmittance for application as transparent conductive electrodes in light emitting diodes(LEDs)and solar cells

Comparison of four promoters for transient expression of RFP reporter gene in cultured Bombyx mori cells (Bm-e-HNU5)

以红色荧光蛋白基因(RFP)为报告基因,构建含4种不同启动子的重组表达质粒,用脂质体介导法转染家蚕Bombyxmori细胞(Bm-e-HNU5),观察家蚕细胞质肌动蛋白4基因启动子(A4)、α微管蛋白基因启动子(α-tub)、蚕丝心蛋白重链基因启动子(Fib)和家蚕核型多角体病毒早期即刻蛋白基因启动子(IE)4种启动子调控RFP报告基因在家蚕细胞内的瞬时表达情况。构建的重组表达质粒pDsRed-α-tub、pDsRed-A4、pDsRed-IE和pDsRed-Fib经双酶切和PCR鉴定正确无误。转染和转录实验结果表明,除了pDsRed-A4外,其他3种重组质粒在Bm-e-HNU5细胞中都得到高转染率,α-tub、IE和Fib可依次增强RFP报告基因在家蚕细胞内的瞬时表达活性。The red fluorescent protein reporter gene (RFP) was used to construct recombinant plasmids containing four different promoters, i. e., the cytoplasmic actin4 promoter (A4), α-tubulin promoter (α-tub)from silkworm, the Bombyx mori nuclear polyhedrosis virus immediate early protein promoter (IE) and the fibroin heavy chain gene promoter (Fib), respectively. These recombinant plasmids, i. e., pDsRed-A4,pDsRed-α-tub,pDsRed-Fib and pDsRed-IE, had been constructed successfully by restriction enzyme digestion and PCR analysis, and then were transfected into B. mori cell lines (Bm-e-HNU5) by lipid-mediated method to observe the ability of the four promoters to drive RFP reporter gene transient expression in cells. Transfection and transcription experiments indicated that except pDsRed-A4, the other three kinds of recombinant plasmids all transfected Bm-e-HNU5 obviously. The promoters of α-tub, IE and Fib enhanced the transient expression activity of RFP reporter gene in the Bm-e-HNU5, and their activity strengthened sequentially.国家自然科学基金项目(39870410

Design and Fabrication of Al_2O_3/SiO_2 Double-Layer Antireflection Coatings on 4H-SiC Substrate

在4H-SiC基底上设计并制备了Al2O3/SiO2紫外双层减反射膜,通过扫描电镜(SEM)和实测反射率谱来验证理论设计的正确性。利用编程计算得到Al2O3和SiO2的最优物理膜厚分别为42.0nm和96.1nm以及参考波长λ=280nm处最小反射率为0.09%。由误差分析可知,实际镀膜时保持双层膜厚度之和与理论值一致有利于降低膜系反射率。实验中应当准确控制SiO2折射率并使Al2O3折射率接近1.715。用电子束蒸发法在4H-SiC基底上淀积Al2O3/SiO2双层膜,厚度分别为42nm和96nm。SEM截面图表明淀积的薄膜和基底间具有较强的附着力。实测反射率极小值为0.33%,对应λ=276nm,与理论结果吻合较好。与传统SiO2单层膜相比,Al2O3/SiO2双层膜具有反射率小,波长选择性好等优点,从而论证了其在4H-SiC基紫外光电器件减反射膜上具有较好的应用前景。Al2O3/SiO2 double-layer UV antireflection coatings were designed and fabricated on 4H-SiC substrate,and the validity of theoretical design was further verified by scanning electron microscope (SEM) and reflection spectrum. The optimal physical thickness of Al2O3 and SiO2 is 42.0 nm and 96.1 nm respectively by programming calculation. And then the minimum reflectance of 0.09% is obtained at reference wavelength λ=280 nm. According to error analysis,keeping the sum of double-layer thickness consistent with theoretical value is helpful to reduce the reflectance. In addition,the refractive index of SiO2 should more accurate and the refractive index of Al2O3 should be controlled close to 1.715 in the experiment. Al2O3/SiO2 double-layer coatings were deposited on 4H-SiC substrate by electron beam evaporation and the physical thickness is 42 nm and 96 nm respectively. SEM images show that the deposited layers and the substrate perform good adhesion to each other. The practical minimum reflectance is 0.33% at λ=276 nm which is close to theoretical value. Compared with conventional SiO2 single layer,Al2O3/SiO2 double-layer coatings show low reflectance and better wavelength selectivity. These results make the possibility for 4H-SiC based UV optoelectronic devices with Al2O3/SiO2 films as antireflection coatings

The Characterization of InGaN and InGaN/GaN Quantum Wells Grown by LP-MOCVD

【中文摘要】 利用 MOCVD系统在 Al2 O3衬底上生长 In Ga N材料和 In Ga N/ Ga N量子阱结构材料。研究发现 ,In Ga N材料中 In组份几乎不受 TMG与 TMI的流量比的影响 ,而只与生长温度有关 ,生长温度由 80 0℃降低到 74 0℃ ,In组份的从 0 .2 2增加到 0 .4 5 ;室温 In Ga N光致发光光谱 (PL)峰全半高宽 (FWH M)为 15 .5 nm;In Ga N/ Ga N量子阱区 In Ga N的厚度 2 nm,但光荧光的强度与 10 0 nm厚 In Ga N的体材料相当。 【英文摘要】 InGaN bulk material and InGaN/GaN quantum well were grown by low pressure metal organic chemical vapor deposition(LP MOCVD),and they were characterized by X ray and photo luminescence(PL) maximum at room temperature.The PL full width of half of InGaN grown at 800 ℃ is 15.5 nm at room temperature and the peak wavelength is 437 nm.The In composition in InGaN did not dependent on the ratio of TMG and TMI but on the growth temperature and the In content increases from 0.22 at 800 ℃ to 0.45 at 740 ℃.The In com...福建省自然科学基金资助项目 (E9820001) ; 国家教育部高等学校骨干教师资助计划项目资