掺氧氮化硅发光二极管的发光特性研究

采用等离子体增强化学气相沉积方法低温制备非晶氮化硅薄膜,在低温下以氧气为气源,等离子体氧化非晶氮化硅薄膜,以这层薄作为有源层制备电致发光器件。实验结果表明以此方法制备的器件在正向偏置电压下可观测到强烈的黄绿光,发光峰位于540 nm,而且电致发光开启电压低,仅为6 V,功耗小。光致发光谱和电致发光谱测量表明发光来自同一种发光中心,即与Si-O相关的发光中心。     

电子束蒸发沉积ZAO薄膜正交试验

采用电子束真空蒸发沉积薄膜的方法(EBED)制备了ZnO:Al(ZAO)透明导电薄膜.用正交试验法设计试验,并分析了制备ZAO薄膜的主要影响因素(沉积厚度、沉积速率、基片温度)对薄膜性能(透射率、电阻率)的作用.试验结果表明:采用EBED法沉积制备ZAO薄膜时,沉积速率控制为1nm/s、沉积厚度为800nm、基片温度为2 50℃,镀膜系统工作稳定,沉积薄膜的性能较好.     

偏置靶材离子束沉积法制备硅锗薄膜的表面粗糙度研究

采用偏置靶材离子束沉积工艺,在相同的沉积参数条件下,在硅、玻璃以及蓝宝石三种不同的衬底上分别制备了相同厚度的纯硅和纯锗薄膜。利用原子力显微镜,研究了两种非晶薄膜在不同衬底上的二维、三维表面形貌和表面粗糙度。结果表明:纯锗薄膜具有较大的均方根粗糙度,均达到了8 nm以上,其中沉积在硅衬底上的纯锗薄膜的均方根粗糙度最大,达到了11.16 nm;而纯硅薄膜的均方根粗糙度较小,均在3 nm以下,其中沉积在硅衬底上的纯硅薄膜的均方根粗糙度最小,仅有0.47 nm。     

并五苯场效应管的电学特性

介绍了用高真空中热蒸发镀膜的方法制备并五苯薄膜场效应晶体管.作为场效应管半导体层的并五苯薄膜沉积在p型Si(100)(14.0～20.0 Ω·cm)衬底上.场效应管中并五苯薄膜厚度为70nm,源极、漏极和栅极(Au)的厚度均为50nm,绝缘层SiO2的厚度为300nm,沟道宽度为190μm,沟道长度为15μm.用AFM表征了并五苯薄膜表面形貌,并研究了薄膜生长速率对并五苯场效应晶体管电学特性的影响.在薄膜生长速率为0.24和1.36 nm/min时,场效应管的载流子迁移率分别为2.7×10-4和2.2×10-6 cm2/(V·s).     

p型微晶硅薄膜的沉积及其在微晶硅薄膜太阳电池中的应用

采用等离子体化学气相沉积（PECVD）方法制备了硼掺杂微晶硅薄膜和微晶硅薄膜太阳电池.研究了乙硼烷含量、p型膜厚度及沉积温度对硼掺杂薄膜生长特性和高沉积速率的电池性能的影响.通过对p型微晶硅薄膜沉积参数的优化,在本征层沉积速率为0.78nm/s的高沉积速率下,制备了效率为5.5%的单结微晶硅薄膜太阳电池.另外,对p型微晶硅薄膜的载流子疏输运机理进行了讨论.     

p型微晶硅薄膜的沉积及其在微晶硅薄膜太阳电池中的应用

采用等离子体化学气相沉积(PECVD)方法制备了硼掺杂微晶硅薄膜和微晶硅薄膜太阳电池.研究了乙硼烷含量、p型膜厚度及沉积温度对硼掺杂薄膜生长特性和高沉积速率的电池性能的影响.通过对p型微晶硅薄膜沉积参数的优化,在本征层沉积速率为0.78nm/s的高沉积速率下,制备了效率为5.5%的单结微晶硅薄膜太阳电池.另外,对P型微晶硅薄膜的载流子疏输运机理进行了讨论.     

并五苯场效应管的电学特性

介绍了用高真空中热蒸发镀膜的方法制备并五苯薄膜场效应晶体管.作为场效应管半导体层的并五苯薄膜沉积在p型Si(100)(14.0～20.0 Ω·cm)衬底上.场效应管中并五苯薄膜厚度为70nm,源极、漏极和栅极(Au)的厚度均为50nm,绝缘层SiO2的厚度为300nm,沟道宽度为190μm,沟道长度为15μm.用AFM表征了并五苯薄膜表面形貌,并研究了薄膜生长速率对并五苯场效应晶体管电学特性的影响.在薄膜生长速率为0.24和1.36 nm/min时,场效应管的载流子迁移率分别为2.7×10-4和2.2×10-6 cm2/(V·s).     

磁控溅射NiO/ZnO透明异质结二极管及其光电特性研究

采用磁控溅射方法在ITO玻璃基板上沉积NiO,ZnO,AZO三层透明氧化物薄膜,成功制备了NiO/ZnO透明异质结二极管.实验结果表明,PN结展示出明显的I-V整流特性,正向开启电压1V;在氙灯光照条件下,二极管反向电流在5V偏置时,达到1.5 mA.二极管在可见光的平均透过率约为25%.     

a-C:F薄膜的工艺及热稳定性研究

以CF4和CH4为源气体,用PECVD法制备了不同沉积条件下的a-C:F薄膜,测量了薄膜的厚度,研究了薄膜沉积速率和沉积工艺的关系,用傅立叶变换红外谱(FTIR)分析了薄膜的化学键结构,用扫描电镜和原子力显微镜分析了薄膜表面形貌,对薄膜在真空中进行了退火,研究了薄膜的热稳定性.实验表明,沉积速率在5～8 nm/min之间,薄膜表面平整、致密,在300℃内有较好的热稳定性.     

沉积速率对H4膜光学带隙及激光损伤特性的影响

采用电子束热蒸发技术在石英基底上制备了H4薄膜,并对其光学和激光损伤特性进行了研究。根据透射率谱计算出薄膜的光学带隙发现, 光学带隙随着沉积速率的降低而增大, 其值大小在4.66～4.73eV。椭偏测试结果表明,当沉积速率从0.92nm/s、0.17nm/s、0.08nm/s降低到0.03nm/s时,薄膜折射率从1.955、1.919、1.901降低到 1.895(1064nm)。所有 样品的消光系数量级均优于10－5,说明薄膜表现出极小的吸收。薄膜的激光损伤形 貌和激光损伤 阈值(LIDT)受沉积速率的影响不大,同一激光能量作用下 ,薄膜的损伤斑大小基本一致,但0.92nm/s 时制备的薄膜,其损伤区与未损伤区存在相互交错现象。当沉积速率从0.03nm/s变化到 0.92nm/s时,薄膜 激光损伤阈 值在16～17J/cm²(1064nm,10ns)之间。     

Effect of electron beam evaporation process parameters on infrared refractive index of Ge film

Ge films were prepared at different deposition temperatures and ion source bias voltage using the electron beam evaporation. The infrared refractive index was obtained by spectral inversion. Results show that the refractive index becomes larger as the deposition temperature increases. The maximum refractive index at the wavelength of 4 000 nm is 4.274 with the deposition temperatures of 210 °C. The refractive index of film decreases first and then increases as the bias voltage increases. When the ion source bias voltage is 120 V, the refractive index of the film is the smallest. The difference in extinction coefficient of Ge films prepared by different process parameters is small.     

AlGaN MSM结构日盲型紫外探测器

采用低压-金属有机化学气相沉积(MOCVD)法在(0001)方向的AlN/蓝宝石模板上生长得到Al组分为40%的AlGaN材料,设计并制作了MSM型AlGaN日盲紫外探测器。通过HRXRD,SEM,AFM对AlGaN材料进行了表征,结果表明:该材料为六方相结构,且应变程度很小,粗糙度(RMS)为1.32 nm。通过测试器件在230³20 nm之间、在不同偏压下的光谱响应曲线,发现器件的截止波长在285 nm附近,截止边很陡峭;器件的峰值响应波长为275 nm;在7 V偏压下,器件峰值响应度达到最大2.8 mA/W;零偏压下,器件的暗电流1×10-13A,器件的暗电流很小。     

Structural and electrical resistivity characteristics of vacuum arc ion deposited zirconium nitride thin films

Zirconium nitride (ZrN) thin films were grown on glass and aluminum substrates using a dual cathodic arc ion deposition technique. The effects of various negative bias voltages and flow ratios of N₂/Ar on the stoichiometric ratio of nitrogen to zirconium (N/Zr), deposition rate, structure, surface morphology and electrical resistivity of the ZrN layer were investigated. Rutherford backscattering spectroscopy measurements indicated a drop in the deposition rate and a slight increase in stoichiometric ratio (N/Zr) with the increase of bias voltage up to −400 V, although the latter still remained slightly less than unity (~0.92). Deposition rate of the film showed an increase with the argon addition. X-ray diffraction patterns depicted mostly polycrystalline nature of the films, with preferential orientation of (2 0 0) planes in the −100 V to −300 V bias voltage range. For 70–50% nitrogen and at a bias voltage of −400 V, the (1 1 1) orientation of ZrN film predominated. The films were smoother at a lower bias of −100 V, while the roughness increased slightly at a higher bias voltage possibly due to (increased) preferential re-sputtering of zirconium-rich clusters/islands. Changes in the resistivity of the films were correlated with stoichiometry, crystallographic orientation and crystalline quality.     

A p-silicon nanowire/n-ZnO thin film heterojunction diode prepared by thermal evaporation

This paper represents the electrical and optical characteristics of a SiNW/ZnO heterojunction diode and subsequent studies on the photodetection properties of the diode in the ultraviolet （UV） wavelength region. In this work, silicon nanowire arrays were prepared on p-type （100）-oriented Si substrate by an electroless metal deposition and etching method with the help of ultrasonication. After that, catalyst-free deposition of zinc oxide （ZnO） nanowires on a silicon nanowire （SiNW） array substrate was done by utilizing a simple and cost-effective thermal evaporation technique without using a buffer layer. The SEM and XRD techniques are used to show the quality of the as-grown ZnO nanowire film. The junction properties of the diode are evaluated by measuring current-voltage and capacitance-voltage characteristics. The diode has a well-defined rectifying behavior with a rectification ratio of 190 at -t-2 V, turn-on voltage of 0.5 V, and barrier height is 0.727 eV at room temperature under dark conditions. The photodetection parameters of the diode are investigated in the bias voltage range of ± 2 V. The diode shows responsivity of 0.8 A/W at a bias voltage of 2 V under UV illumination （wavelength = 365 nm）. The characteristics of the device indicate that it can be used for UV detection applications in nano-optoelectronic and photonic devices.     

Electrical properties of sputtered (Ba, Sr)TiO3 thin films prepared by two-step deposition method

The influence of two-step deposition on the electrical properties of sputtered (Ba,Sr)TiO₃ thin films was investigated. BST thin films with thickness 40 nm were deposited by a simple two-step radio frequency-magnetron sputtering technique, where the BST thin film consisted of a seed layer and a main layer. The dielectric constant was strongly dependent on the thickness of seed layer, but there was no dependence on deposition temperature of the seed layer. For a 2 nm seed layer, the dielectric constants were higher by about 29% than those of single-step BST thin films due to higher crystallinity and the leakage current was nearly the same as that of a single-step sample in bias voltage from −2 to 2.5 V. However, an improvement of the dielectric constant was not observed for samples having above 4 nm thick seed layers. A 40 nm thick BST film with 2 nm thick seed layer deposited by a two-step method exhibited a SiO₂ equivalent thickness of 0.385 nm and a leakage current density of 2.74 × 10⁻⁸A/cm²at+1.5V after post-annealing under an atmosphere of flowing N₂ for 30 min at 750°C.     

High-speed photoconductive switch based on low-temperature GaAs transferred on SiO/sub 2/-Si substrate

In this letter, we report high-speed photoconductive switches based on low-temperature (LT) grown GaAs on Si substrate. Epitaxially grown LT GaAs was separated from its substrate, transferred on an SiO/sub 2/-coated Si substrate and integrated with a transmission line. The 10/spl times/20-/spl mu/m/sup 2/ switches exhibit high breakdown voltage and low dark currents (<10/sup -7/ A at 100 V). The photoresponse at 810 nm shows electrical transients with /spl sim/0.55-ps full-width at half-maximum and /spl sim/0.37-ps decay time, both independent on the bias voltage up to the tested limit of 120 V. The photoresponse amplitude increases up to /spl sim/0.7 V with increased bias and the signal bandwith is /spl sim/500 GHz. The freestanding LT GaAs switches are best suited for ultrafast optoelectronic testing since they can be placed at virtually any point on the test circuit.     

Enhanced negative substrate bias degradation in nMOSFETs with ultrathin plasma nitrided oxide

The degradation induced by substrate hot electron (SHE) injection in 0.13-/spl mu/m nMOSFETs with ultrathin (/spl sim/2.0 nm) plasma nitrided gate dielectric was studied. Compared to the conventional thermal oxide, the ultrathin nitrided gate dielectric is found to be more vulnerable to SHE stress, resulting in enhanced threshold voltage (V/sub t/) shift and transconductance (G/sub m/) reduction. The severity of the enhanced degradation increases with increasing nitrogen content in gate dielectric with prolonged nitridation time. While the SHE-induced degradation is found to be strongly related to the injected electron energy for both conventional oxide , and plasma-nitrided oxide, dramatic degradation in threshold voltage shift for nitrided oxide is found to occur at a lower substrate bias magnitude (/spl sim/-1 V), compared to thermal oxide (/spl sim/-1.5 V). This enhanced degradation by negative substrate bias in nMOSFETs with plasma-nitrided gate dielectric is attributed to a higher concentration of paramagnetic electron trap precursors introduced during plasma nitridation.     

MoO3作空穴注入层的绿光有机电致发光器件制备及其性能研究

用真空热蒸镀的方法制备了绿光有机电致发光器件,并对其工艺流程进行了详细的描述。器件结构为ITO/MoO3(xnm)/N,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,18-biphenyl)-4,4-diamine(NPB)(40nm)/tris(8-hydroxyquinoline)aluminum(Alq3)(60nm)/LiF(1nm)/Al(150nm),其中x=0,5nm。实验中,对ITO基片进行氧等离子体表面处理,能够有效减小ITO表面的接触角。通过对器件的光电性能测试,研究了MoO3作空穴注入层对有机电致发光器件性能的影响。实验结果表明,空穴注入层MoO3的最高占据分子轨道(HOMO)能级较好的与ITO功函数匹配,降低了空穴注入势垒,提高了器件的发光亮度和效率。当外加电压小于10V时,器件的电流密度随外加电压的增加而增加,但变化不明显;当外加电压大于10V时,器件的电流密度明显增强,发光色度几乎不随驱动电压的改变而改变,色坐标稳定在(0.36,0.55)附近。     

纳米光学金刚石薄膜的分析与改进

由于极其优良的热学和光学性能,纳米金刚石薄膜极有可能应用于背投电视的激光光学窗口。文章通过在热丝辅助化学气相沉积法中采用偏压增强成核(BEN-HFCVD) ,成功地在(100)硅衬底上制得了适于作为光学窗口的高质量的光学级纳米金刚石薄膜,采用的偏压为-30 V。通过表征制备的纳米金刚石薄膜,发现它具有光滑的表面,表面均方根粗糙度(RMS)约为10 nm,并且对自支撑纳米金刚石薄膜进行透射光谱分析得到其透射率达到了50 %。     

The amorphous Si/SiC heterojunction color-sensitive phototransistor

An amorphous Si/SiC heterojunction color-sensitive phototransistor was successfully fabricated by plasma-enhanced chemical vapor deposition. The structure is glass/ITO/a-Si(n⁺-i)/a-SiC(p⁺-i-n⁺)/Al. The device is a bulk barrier transistor with wide-bandgap amorphous SiC emitter and base. The phototransistor revealed a very high optical gain of 40 and a response speed of 10 µs at an input light power of 5 µW and a collector current of 0.12 mA at a voltage of 14 V. The peak response occurs at 610 nm under 1-V bias and changes to 420 and 540 nm under 7- and 13-V biases, respectively.