Direct fabricating patterns using stamping transfer process with PDMS mold of hydrophobic nanostructures on surface of micro-cavity

The transfer stamping process has been used to fabricate thin-film pattern in recent years. Due to the characteristics of the materials of molds and inks, residual inks on the cavities of mold and residual layers on the substrate are still a problem. To solve the problem, we present a concept for fabrication of hydrophobic nanostructures on the cavities of microstructures of the mold, which can effectively decrease the ink residing on the cavities of the mold during coating. First, the periodic nanopores are fabricated on the anodic aluminum oxide (AAO). Second, AAO membrane is employed as the template for fabricating nanostructures on the PC film by embossing. And then, by partial protrusion of the nano-structured PC film into the micro-holes of the mold, an array of protruded convex microstructures is formed. After that, polydimethylsiloxane (PDMS) mold is casted from the embossed PC film. The contact angle of nanostructures on the micro-cavities of PDMS mold is about 145°. Micro-patterns with no residual layers have been successfully transferred on the poly(ethylene terephthalate) (PET) substrate using a transfer stamping process with this PDMS mold.     

InAlN薄膜MOCVD外延生长研究

为了研究不同压力和不同模板对InA lN薄膜外延生长的影响,分别选取以GaN为模板时生长压力为4.00、6.67和13.33 kPa,压力为4.00 kPa时模板为GaN和A lN这两组条件进行实验比较。研究发现,随着生长压力的增加,样品中In含量降低,样品的粗糙度则随压力的增加而增大;压力为4.00 kPa时,分别以摇摆曲线半高宽(FWHM)为86.97″的A lN和224.1″的GaN为模板,发现A lN模板上生长的InA lN样品(002)和(102)峰的FWHM值及表面粗糙度比上述GaN为模板生长的InA lN样品都要小很多。综合以上结果可初步得知:降低压力可以优化InA lN薄膜的表面形貌,增加In组分含量;采用高质量的A lN作模板能生长出晶体质量和表面形貌都比较好的InA lN薄膜。     

A novel fabrication of polymer film with tapered sub-wavelength structures for anti-reflection

This paper presents a cost-effective method to fabricate tapered sub-wavelength structures (SWSs) on the polycarbonate (PC) film using gas-assisted hot embossing with anodic aluminum oxide (AAO) template. The AAO template with array of high-aspect-ratio submicron holes was fabricated using a two-step anodization process. The soften polymer is then pressurized by gas to fill deep into the nano-holes, tapered SWSs could be generated by directly separating the PC film from AAO template during the de-molding process. The heights were up to about 260 nm. The fabricated PC film reduces the reflectivity from 8.9% in a bare film to 2% with tapered SWSs at the wavelength of 550 nm. The AAO template can be used repeatedly.     

Fabrication of high density nano-pillar type phase change memory devices using flexible AAO shaped template

In this study, the high density nano-pillar type phase change memory was fabricated using duplicating nano-patterns of the anodic alumina oxide (AAO) by nanoimprint process. The high density nano-hole array of AAO template was transferred to the flexible PVC polymer template using hot embossing method. To use the flexible AAO shaped template for UV-NIL, the high density nano-pillar type Ge₂Sb₂Te₅ patterns were fabricated, and the electrical properties of the device were evaluated by conducting atomic force microscopy, connected electrical measurement system. To use the flexible AAO shaped template for UV-NIL, high density GST pattern could be fabricated even on the flexible polyimide (PI) substrate.     

阳极氧化铝(AAO)模板法制作的直径和长度一致的碳纳米管

我们在铝衬底上制作了不同参数条件下的阳极氧化铝(AAO)模板.通过改变初次阳极化时间来得到不同尺寸的纳米孔.改变初次阳极化时间可容易地调节,而使用刻蚀技术又可以控制氧化铝孔的长度.在该研究中,控制阳极极化和刻蚀参量成功地制备了不同直径和不同长度的AAO纳米孔.在AAO模板的竖直沟道中生长了方向性强的碳纳米管,而AAO纳米孔的直径和长度可以控制这一过程.通过二次阳极极化法制备了有着六边形孔洞排列方式的纳米AAO模板.由于AAO纳米孔的直径和长度依赖于阳极化参量,故通过控制阳极化参量就可控制AAO纳米孔的直径和长度.     

Fabrication of gold sub-wavelength pore array using gas-assisted hot embossing with anodic aluminum oxide (AAO) template

This paper reports a novel and effective method for the fabrication of gold sub-wavelength pore array using gas-assisted hot embossing. The novel fabrication comprises the fabrication of AAO template with high order pore array, sputter-coating of gold and gas-assisted hot embossing. AAO template is fabricated by a two-step anodization process. It is then coated with gold (100 nm thick). The gold sub-wavelength pore array is finally formed by using gas-assisted hot embossing process. The transmission spectra of gold sub-wavelength pore array are measured in several conditions such as air, water and glycerol/water mixture. The detection shows significant shift in the wavelength of resonance peak. The gold sub-wavelength pore array can be employed as optical biosensors.     

Anodized Aluminum Oxide/Polydimethylsiloxane Hybrid Mold for Roll‐to‐Roll Nanoimprinting

Two types (hard and soft) of the molds are widely used in nanoimprint lithography for a high throughput over a large area, and high‐resolution parallel patterning. Although hard molds have proven excellent resolutions and can be used at high temperatures, cracks often occur in the mold in addition to the requirement of high imprinting pressure. On the other hand, though soft molds can operate at lower pressures, they give poor pattern resolution. Here, a novel hybrid mold of anodized aluminum oxide (AAO) template attached to a flexible polydimethylsiloxane (PDMS) plate is introduced. Due to the flexible nature of PDMS, various polymer nanostructures are obtained on flat and curved substrates without crack formation on the AAO mold surface. Furthermore, the hybrid mold is successfully used for roll‐to‐roll imprinting for the fabrication of high density array of various shaped polymeric nanostructures over a large area.     

直流电沉积制备一维ZnSe半导体纳米材料

用二次阳极氧化法制备了多孔阳极氧化铝(AAO)模板。以AAO为模板,在ZnSO4、Na2SO4和H2SeO3的混合水溶液中进行直流电沉积了ZnSe半导体纳米线。SPM、TEM测试表明,模板表面形成模孔大小一致、排列规则的阵列。ZnSe纳米线的直径约为60nm,长度约为0.5μm并与模板的孔径和深度一致。在制备过程中,无需去除AAO的基底,喷金或预镀金属等处理,直接在AAO纳米孔内电沉积,制备纳米线。该方法简单、有效并且容易获得有序的半导体纳米线阵列。     

Reproducibility of growing AlGaN/GaN high-electron-mobility-transistor heterostructures by molecular-beam epitaxy

High-quality GaN/AlGaN high-electron-mobility transistors (HEMT) characterized by room temperature mobilities of 1000 cm² V⁻¹ s⁻¹ and sheet electron densities in the range of 3×10¹²–2×10¹³ cm⁻² have been grown by reactive molecular-beam epitaxy on insulating C-doped GaN template layers. Growth data and mobility values resulting from over 50 HEMT growth experiments on 2 in. diameter sapphire wafers are presented to show the remarkable overall high yield and reproducibility of the HEMT structures grown by this method. The use of insulating C-doped GaN buffer layers has greatly increased reproducibility of the device structures by ensuring device isolation through controlled carbon doping. Moreover, an undoped GaN channel layer of remarkably low defect density and high mobility can be grown on the C-doped GaN template with high reproducibility. Precise control of the growth temperature was key to achieving the high quality and reproducibility of the structures.     

Ultradense GaN nanopillar and nanopore arrays by self-assembly nanopatterning

We report on the details of controlled fabrication of highly crystalline gallium nitride (GaN) two-dimensional highly periodic ultradense nanopore and nanopillar arrays by self-assembly nanopatterning. Nanopore synthesis relies on the use of anodized alumina oxide template as a mask for dry etching of GaN top surface using chlorine gas. The inverse patterning is accomplished by site-selective deposition of metal nanodot array by e-beam evaporation of Ni through the pores of the template; after which the template is removed and dry etching is performed. The formed patterns demonstrate an excellent hexagonal order and uniformity according to fast Fourier transformation performed. The presented approach is robust, highly reproducible, and technically undemanding. Moreover, unreduced crystallinity of the produced nanopillars and nanopores was confirmed with Raman measurements, which suggests their possible use as future substrates for engineering advanced nano-optoelectronic devices and sensors.     

AAO模板浸渍法制备Au纳米线

用模板浸渍法成功地在多孔阳极氧化铝(AAO)模板里制备了Au纳米线。在这种方法中,AAO模板的孔壁在HAuCl4里浸湿,取出后通过热处理形成Au纳米线。使用扫描电子显微镜和X射线对Au纳米线的微观形貌和结构进行了表征。扫描电镜图片表明在AAO孔中形成了直的并且表面粗糙的金纳米线,纳米线直径约50 nm。X射线衍射图表明,金纳米线具有面心立方(FCC)结构。最后,研究了Au纳米线的形成机理。     

Cu 纳米线的制备及其力学性能的研究

采用购买的直径为40～50 nm的AAO模板,利用直流电沉积方法在AAO模板上制备了Cu纳米线.TEM观察发现,Cu 纳米线的直径为(45±5)nm,与AAO模板的内孔 直径一致.利用碳膜卷曲的方法,在JEOL 2010F型场发射透射电子显微镜中对单根 Cu 纳米线进行了原位弯曲变形实验.实验发现,存在于纳米线内部的孪...     

蓝宝石衬底上HVPE-GaN厚膜生长

采用氢化物气相外延(HVPE)方法,以蓝宝石作衬底,分别在MOCVD-GaN模板和蓝宝石衬底上直接外延生长GaN.模板上的GaN生长表面平整、光亮,但开裂严重.其(0002)的双晶衍射半高宽最低为141″;蓝宝石衬底上直接生长GaN外延层质量较差,其双晶衍射半高宽为1688″,但不发生开裂.HCl的载气流量对预反应有很大的影响.应力产生于外延层和衬底之间的界面处,界面孔洞的存在可以释放应力,减少开裂.光致发光(PL)谱中氧杂质引起强黄光发射.     

AAO模板的湿法刻蚀研究

利用二次阳极氧化法制备多孔氧化铝(AAO)模板,然后用NaOH、磷铬酸和不同质量分数的H3PO4等溶液,对AAO模板进行湿法刻蚀.研究了刻蚀时间与AAO模板质量减少之间的变化关系.结果表明,质量分数为3%的H3PO4溶液是最为温和的刻蚀荆,它在刻蚀过程中AAO模板的质量减少跟刻蚀时间呈较好的线性关系.SEM测试表明,刻蚀后的AAO模板表面存在大量的氧化铝纳米线,它们是在刻蚀的过程中产生的,并影响着刻蚀速率.通过调节刻蚀时间,可实现对AAO模板的精确可控刻蚀,这对制备纳米器件具有重要意义.     

MOCVD epitaxy of InAlN on different templates

InAlN epilayers were grown on high quality GaN and A1N templates with the same growth parameters. Measurement results showed that two samples had the same In content of～16%,while the crystal quality and surface topography of the InAlN epilayer grown on the AlN template,with 282.3"（002） full width at half maximum （FWHM） of rocking curve,313.5"（102） FWHM,surface roughness of 0.39 nm and V-pit density of 2.8×10⁸ cm^-2,were better than that of the InAlN epilayer grown on the GaN template,309.3",339.1",0.593 nm and 4.2×10⁸ cm^-2.A primary conclusion was proposed that both the crystal quality and the surface topography of the InAlN epilayer grown on the AlN template were better than that of the InAlN epilayer grown on the GaN template. Therefore,the AlN template was a better choice than the GaN template for getting high quality InAlN epilayers.     

GaN衬底上纳米点阵列的制备及其应用研究

研究了纳米掩膜在材料外延生长及器件制备中的应用.通过电化学腐蚀和电子束蒸发方法在GaN表面生成Ni和SiO<,2>纳米点阵列,经过等离子体刻蚀在Ni/GaN模板上形成GaN纳米锥形结构;利用氢化物气相外延(HVPE)方法,在SiO<,2>/GaN模板上制备厚膜GaN材料.X射线衍射(XRD)和光致发光(PL)谱测试表明...     

Sol-Gel法制备ZnO纳米点阵结构

以Al2O3膜为模板,通过溶胶-凝胶浸渍法,经过干燥、高温加热制备了ZnO纳米点阵结构.SEM结果表明,AAO模板孔遭呈六角形排布,孔道垂直无交叉,孔径为50mm左右,在AAO模板内装入的ZnO为纳米颗粒.XRD结果表明,AAO模板为非晶结构,孔内ZnO具有多晶纤锌矿结构.PL谱结果表明,ZnO/AAO组装体系表现出了很强的紫外发射.     

The effect of substrate surface roughness on GaN growth using MOCVD process

Efficiency and lifetime of light emitting diodes and laser diodes inversely depend on defect density of the crystal, and reduction of defect density is accomplished by a proper choice of substrate or a deliberate modification of the substrate surface. Buffer growth or nitridation can yield an atomically flat surface and the roughness of a substrate surface for GaN deposition can be controlled by either method such that lateral film growth can be promoted. The effect of nanoscale surface roughness on photoluminescence and crystal quality of GaN/Al₂O₃ (0001) has been studied. The optimal conditions for N₂-nitridation or/and GaN-buffer growth correlate well with the minimum surface roughness and surface morphology as determined by atomic force microscopy and it is suggested that this can be used for process optimization of GaN film growth.     

图案化铜纳米线阵列的制备

采用紫外光刻法制得图案化的阳极氧化铝模板。在模板上蒸镀金膜后,采用电化学沉积法制备了铜纳米线,用扫描电子显微镜观察,研究了最佳电化学沉积时间。结果表明,铜纳米线阵列的图案与掩膜的图案完全一致,呈直径约5μm的圆形。铜纳米线的长度随沉积时间的增加而增长,沉积时间20min,即可制得长度约5μm的铜纳米线阵列结构。在此基础上可研制微器件。     

阳极氧化铝模板应用研究新进展

论述了AAO模板以其独特的六角有序纳米结构,组装1-D材料取得的成功,指出目前关注重点为AAO的应用研究.指出由于AAO模板易脆、存在绝缘阻挡层等缺点,其应用研究进展不大.阐述了为克服上述困难,将AAO模板转移到Si衬底或玻璃衬底上的可行性.分析表明,目前AAO模板的应用研究主要集中在发光器件和存储器件上,其他研究报导还很少.对近年来人们利用AAO模板开展应用研究方面的进展做了回顾和评述以其进一步加快AAO模板的应用.