Optimization of large-area YBa_(2)Cu_(3)O_(7-δ)thin films by pulsed laser deposition for planar microwave devices

This paper presents high quality YBa_(2)Cu_(3)O_(7-δ)(YBCO)thin films on LaAlO_(3)substrate for microwave devices prepared by pulsed laser deposition(PLD).The double-sided YBCO films cover a large area and have been optimized for key parameters relevant to microwave device applications,such as surface morphology and surface resistance(R_(s)).This was achieved by improving the target quality and increasing the oxygen pressure during deposition,respectively.To evaluate the suitability of the YBCO films for microwave devices,a pair of microwave filters based on microstrip fabricated on films from this work and a commercial company were compared.The results show that the YBCO films in this work could completely meet the requirements for microwave devices.

Exploration of growth conditions of TaAs Weyl semimetal thin film using pulsed laser deposition

Ta As,the first experimentally discovered Weyl semimetal material,has attracted a lot of attention due to its high carrier mobility,high anisotropy,nonmagnetic properties and strong interaction with light.These make it an ideal candidate for the study of Weyl fermions and applications in quantum computation,thermoelectric devices,and photodetection.For further basic physics studies and potential applications,large-size and high-quality Ta As films are urgently needed.However,it is difficult to grow As-stoichiometry Ta As films due to the volatilization of As during the growth.To solve this problem,we attempted to grow Ta As films on different substrates using targets with different As stoichiometric ratios via pulsed laser deposition(PLD).In this work,we found that partial As ions of the Ga As substrate are likely to diffuse into the Ta As films during growth,which was preliminarily confirmed by structural characterization,surface topography and composition analysis.As a result,the As content in the Ta As film was improved and the Ta As phase was achieved.Our work presents an effective method for the fabrication of Ta As films using PLD,enabling possible use of the Weyl semimetal film for functional devices.

Comparison of ZnO Films Grown on before- and after-vapor Transport Equilibration (VTE) LiAlO_2 Substrates by Pulsed Laser Deposition (PLD)

About φ45 mm LiAlO2 single crystal was grown by Czochralski （Cz） technique. However, the full-width at half-maximum （FWHM） value was high to 116.9 arcsec. After three vapor transport equilibration （VTE） processes, we can obtain high-quality LiAlO2 slice with the FWHM value of 44.2 arcsec. ZnO films were fabricated on as-grown slices and after-VTE ones by pulsed laser deposition （PLD）. It was found that ZnO films on the two slices have similar crystallinity, optical transmittance and optical band gap at room temperature. These results not only show that LAO substrate is suitable for ZnO growth, but also prove that the crystal quality of LAO substrate slightly affects the structural and optical properties of ZnO film.

Preparation and Characterization of Cu-Zn Nano-Structural Ferrite Thin Films Produced by Pulsed Laser Deposition (PLD)

Cu-Zn ferrite nano thin films were deposited from a target of Cu-Zn ferrite onto a sapphire substrate using XeCl excimer laser operating 308 nm with an energy of 225 mJ and a frequency of 30 Hz. Films were deposited from the target onto sapphire (001) substrates heated to 650℃ in an oxygen atmosphere of 100 mTorr. The laser beam was incident On the target face at an angle of 45°. Studies on crystal structure were done by X-ray diffactometry (XRD). The surface texture, cross-section morphology and grain size was observed by JEOL-JSM-6400 scanning electron microscopy, atomic force microscopy (AFM) and magnetic force microscopy (MFM) [Model DI 3000, Digital instruments].

Tribological properties of diamond-like carbon films deposited bv pulsed laser arc deposition

A novel method, pulsed laser arc deposition combining the advantages of pulsed laser deposition and cathode vacuum arc techniques, was used to deposit the diamond-like carbon （DLC） nanofilms with different thicknesses. Spectroscopic ellipsometer, Auger electron spectroscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, scanning electron microscopy and multi-functional friction and wear tester were employed to investigate the physical and tribological properties of the deposited films. The results show that the deposited films are amorphous and the sp2, sp3 and C-O bonds at the top surface of the films are identified. The Raman peak intensity and surface roughness increase with increasing film thickness. Friction coefficients are about 0.1, 0.15, 0.18, when the film thicknesses are in the range of 17-21 nm, 30-57 nm, 67-123 nm, respectively. This is attributed to the united effects of substrate and surface roughness. The wear mechanism of DLC films is mainly abrasive wear when film thickness is in the range of 17-41 nm, while it transforms to abrasive and adhesive wear, when the film thickness lies between 72 and 123 nm.

Preparation of Ga_2O_3 thin film solar-blind photodetectors based on mixed-phase structure by pulsed laser deposition

Gallium oxide(Ga_2O_3) thin films were deposited on a-Al2O3(1120) substrates by pulsed laser deposition(PLD) with different oxygen pressures at 650?C. By reducing the oxygen pressure, mixed-phase Ga_2O_3 films with α and β phases can be obtained, and on the basis of this, mixed-phase Ga_2O_3 thin film solar-blind photodetectors(SBPDs) were prepared.Comparing the responsivities of the mixed-phase Ga_2O_3 SBPDs and the single β-Ga_2O_3 SBPDs at a bias voltage of 25 V,it is found that the former has a maximum responsivity of approximately 12 A/W, which is approximately two orders of magnitude larger than that of the latter. This result shows that the mixed-phase structure of Ga_2O_3 thin films can be used to prepare high-responsivity SBPDs. Moreover, the cause of this phenomenon was investigated, which will provide a feasible way to improve the responsivity of Ga_2O_3 thin film SBPDs.

High temperature thermoelectric properties of highly c-axis oriented Bi_2Sr_2Co_2O_y thin films fabricated by pulsed laser deposition

High-temperature thermoelectric transport property measurements have been performed on the highly c-axis oriented Bi2Sr2Co20v thin films prepared by pulsed laser deposition on LaA1Oa （001）. Both the electric resistivity p and the seebeck coefficient S of the film exhibit an increasing trend with the temperature from 300 K-1000 K and reach up to 4.8 m. cm and 202 V/K at 980 K, resulting in a power factor of 0.85 mW/mK which are comparable to those of the single crystalline samples. A small polaron hopping conduction can be responsible for the conduction mechanism of the film at high temperature. The results demonstrate that the Bi2Sr2Co2Oy thin film has potential application has high temperature thin film thermoelectric devices,

Growth properties of gallium oxide on sapphire substrate by plasma-assisted pulsed laser deposition

Gallium oxide was deposited on a c-plane sapphire substrate by oxygen plasma-assisted pulsed laser deposition(PLD).An oxygen radical was generated by an inductive coupled plasma source and the effect of radio frequency(RF)power on growth rate was investigated.A film grown with plasma assistance showed 2.7 times faster growth rate.X-ray diffraction and Raman spectroscopy analysis showedβ-Ga2 O3 films grown with plasma assistance at 500℃.The roughness of the films decreased when the RF power of plasma treatment increased.Transmittance of these films was at least 80%and showed sharp absorption edge at 250 nm which was consistent with data previously reported.

Pulsed Laser Deposition ZnS Buffer Layers for CIGS Solar Cells

多晶的 ZnS 电影被搏动的激光免职( PLD )在 20 ， 200 ， 400 ，和 600 °C 的不同底层温度在不同生长条件下面在石英玻璃底层上准备，它是扔的化学洗澡( CBD )的一种合适的选择 CdS 作为在 Cu 的缓冲区层(在里面， Ga ) Se 2(帝国参谋总长)太阳能电池。X 光检查衍射研究显示这些电影与锌闪锌矿结构是多晶的，他们沿着立方的阶段 β-ZnS (111 ) 展出优先的取向方向，哪个与由 ZnS 电影由脉搏 plating 技术扔了的 Murali 的 wurtzite 结构的结论的冲突与 wurtzite 是多晶的结构。成年电影的拉曼系列在通常在立方的阶段 β-ZnS 混合物观察的约 350 厘米 −1, 显示出一个 1 模式。平面并且代表性的形态学被扫描电子观察显微镜。稠密的、光滑的、一致谷物通过 PLD 技术在石英玻璃底层上被形成。PLD 扔的 ZnS 的谷物尺寸是比由常规 CBD 方法的 CdS 的小得多的，它作为有害房间性能的主要原因被分析。ZnS 电影的作文被 X 光检查荧光也测量。在这个工作获得的典型 ZnS 电影在 stoichiometric 和仅仅小数量附近 S 富有。在不同温度的精力乐队差距被吸收光谱学测量获得，它与增加免职温度从 3.2 eV 增加到 3.7 eV。ZnS 让一个更宽的精力乐队比 CdS (2.4 eV ) 豁开，它能提高光电的房间的蓝反应。这些结果出现这些代用品缓冲区层材料高质量通过一种所有干燥的技术被准备，它能在帝国参谋总长薄电影太阳能电池的制造被使用。

High-Throughput Multi-Plume Pulsed-Laser Deposition for Materials Exploration and Optimization

A high-throughput multi-plume pulsed-laser deposition(MPPLD) system has been demonstrated and compared to previous techniques. Whereas most com binatorial pulsedlaser deposition(PLD) systems have focused on achieving thickness uniformity using sequential multilayer deposition and masking followed by post-deposition annealing, MPPLD directly deposits a compositionally varied library of compounds using the directionality of PLD plumes and the resulting spatial variations of deposition rate. This system is more suitable for high-throughput compound thin-fllm fabrication.

Microstructure,optical,and photoluminescence properties ofβ-Ga_(2)O_(3)films prepared by pulsed laser deposition under different oxygen partial pressures

Theβ-Ga_(2)O_(3)films are prepared on polished Al_(2)O_(3)(0001)substrates by pulsed laser deposition at different oxygen partial pressures.The influence of oxygen partial pressure on crystal structure,surface morphology,thickness,optical properties,and photoluminescence properties are studied by x-ray diffraction(XRD),atomic force microscope(AFM),scanning electron microscope(SEM),spectrophotometer,and spectrofluorometer.The results of x-ray diffraction and atomic force microscope indicate that with the decrease of oxygen pressure,the full width at half maximum(FWHM)and grain size increase.With the increase of oxygen pressure,the thickness of the films first increases and then decreases.The room-temperature UV-visible(UV-Vis)absorption spectra show that the bandgap of theβ-Ga_(2)O_(3)film increases from4.76 e V to 4.91 e V as oxygen pressure decreasing.Room temperature photoluminescence spectra reveal that the emission band can be divided into four Gaussian bands centered at about 310 nm(~4.0 e V),360 nm(~3.44 e V),445 nm(~2.79 e V),and 467 nm(~2.66 e V),respectively.In addition,the total photoluminescence intensity decreases with oxygen pressure increasing,and it is found that the two UV bands are related to self-trapped holes(STHs)at O1 sites and between two O2-s sites,respectively,and the two blue bands originate from V_(Ga)^(2-)at Ga1 tetrahedral sites.The photoluminescence mechanism of the films is also discussed.These results will lay a foundation for investigating the Ga_(2)O_(3)film-based electronic devices.

Comprehensive Optimization of Electrical and Optical Properties for ATO Films Prepared by Pulsed Laser Deposition

Antimony doped tin oxide（ATO） thin films have been prepared by pulsed laser deposition（PLD） method.The intrinsic effect of Sb dopant,including the Sb content,transition degree between Sb（3＋） and Sb（5＋） and crystallinity on the electrical and optical properties of the ATO thin films is mainly investigated.It is suggested that the transition degree of Sb（3＋） towards Sb（5＋）（Sb（5＋）/Sb（3＋） ratio） is determined by Sb content.When the Sb content is increased to 12 at%,the Sb（5＋）/Sb（3＋） ratio reaches the highest value of 2.05,corresponding to the resistivity of 2.70×10（-3） Ω·cm.Meanwhile,the Burstein-Moss effect caused by the increase of carrier concentration is observed and the band gap of the ATO thin films is broadened to 4.0 eV when the Sb content is increased to 12 at%,corresponding to the highest average optical transmittance of 92%.Comprehensively considering the combination of electrical and optical properties,the ATO thin films deposited with Sb content of 12 at%exhibit the best properties with the highest ＂figure of merit＂ of 3.85×10（-3） Ω（-1）.Finally,an antimony selenide（Sb_2Se_3） heterojunction solar cell prototype with the ATO thin film as the anode has been prepared,and a power conversion efficiency of 0.83%has been achieved.

Properties of multilayer gallium and aluminum doped ZnO(GZO/AZO) transparent thin films deposited by pulsed laser deposition process

Multilayer gallium and aluminum doped ZnO (GZO/AZO) films were fabricated by alternative deposition of Ga-doped zinc oxide(GZO) and Al-doped zinc oxide(AZO) thin film by using pulsed laser deposition(PLD) process. The electrical and optical properties of these GZO/AZO thin films were investigated and compared with those of GZO and AZO thin films. The GZO/AZO (1:1) thin film deposited at 400 °C shows the electrical resistivity of 4.18×10-4 Ω·cm, an electron concentration of 7.5×1020 /cm3, and carrier mobility of 25.4 cm2/(V·s). The optical transmittances of GZO/AZO thin films are over 85%. The optical band gap energy of GZO/AZO thin films linearly decreases with increasing the Al ratio.

STRUCTURE AND SURFACE STUDIES OF Mg_xZn_(1-x)O FILMS GROWN BY PULSED LASER DEPOSITION

The structural and surface properties of high-quality epitaxial cubic MgxZn1-xO films deposited by pulsed laser deposition (PLD) were studied by X-ray diffracti on and atomic force microscopy respectively. For films of about 500nm thick, sca ns over a 30μm × 30μm area revealed a surface roughness Ra of about 100nm. Th is relatively large surface roughness is primarily attributed to the particulate and outgrowth during the PLD process. A good epitaxial growth on LaAlO3 (LAO ) (100) substrates, however has been obtained for composition x = 0.9, 0.7 and 0 .5 with the heteroepitaxial relationship of (100)■∥(100)LAO (out-of-plane) and (011)■∥(010)LAO (in-plane). These structural qualities suggest that cubic Mgx Zn1-xO alloys films have good potential in a variety of optoelectronic device ap plications.

Pulsed Laser Deposition of Boron Carbon Nitride Coatings

oron carbon nitride coatings were synthesized using the pulsed laser deposition method. The hardness of the coatings was measured by a Vickers microhardness tester. It was found that the hardness of the coatings was between 15.45 and 34.05 GPa under a load of 0.5 N. The surface morphology was studied by optical microscopy and atomic force microscopy. There were spherical and irregular shaped particulates in the coatings. The density of the spherical particles was found being increased at high deposition temperatures. The rootmeansquared surface roughness of the coatings was about 4 nm.

Growth of Erbium Dihydride Films under Low Hydrogen Pressure by Pulsed Laser Deposition

Erbium dihydride thin films were prepared by pulsed laser deposition on Si（100） substrates using erbium target under different low hydrogen pressures. The properties of these films were examined by atomic force microscopy, X-ray diffractometer, transmission electron microscopy, and Fourier transform infrared spectroscopy and UV-vis spectroscopy. Surface morphology reveals the smooth surface of these films （RMS： from 0.503 to 2.849 nm）. The presence of obviously-broadened peaks for diffraction planes （111） suggests a presence of very tiny crystallites distributed along a preferred crystallographic orientation. Transmission electron microscopy investigations confirmed the formation of tiny crystallites due to the implantation of erbium ions. Due to the increase of nominal H concentration, the intensity of the broad absorbance from 190-260 nm increased.

Preparation and tribological properties of DLC/Ti film by pulsed laser arc deposition

This paper reports that DLC （diamond like carbon）/Ti and DLC films were prepared by using pulsed laser arc deposition. R-ray diffraction, Auger electron spectroscopy, Raman spectroscopy, atomic force microscopy, nanoindenter, spectroscopic ellipsometer, surface profiler and micro-tribometer were employed to study the structure and tribological properties of DLC/Ti and DLC films. The results show that DLC/Ti film, with I（D）/I（G） 0.28 and corresponding to 76% sp3 content calculated by Raman spectroscopy, uniform chemical composition along depth direction, 98 at% content of carbon, hardness 8.2 GPa and Young＇s modulus 110.5 GPa, compressive stress 6.579 GPa, thickness 46 nm, coefficient of friction 0.08, and critical load 95mN, exhibits excellent mechanical and tribological properties.

Preparation and Properties of IrO_2 Thin Films Grown by Pulsed Laser Deposition Technique

Highly conductive IrO2 thin films were prepared on Si （100） substrates by means of pulsed laser deposition technique from an iridium metal target in an oxygen ambient atmosphere. Emphasis was put on the effect of oxygen pressure and substrate temperature on the structure, morphology and resistivity of IrO2 films. It was found that the above properties were strongly dependent on the oxygen pressure and substrate temperature. At 20 Pa oxygen ambient pressure, pure polycrystalline IrO2 thin films were obtained at substrate temperature in the 300-500℃ range with the preferential growth orientation of IrO2 films changed with the substrate temperature. IrO2 films exhibited a uniform and densely packed granular morphology with an average feature size increasing with the substrate temperature. The room-temperature resistivity variations of IrO2 films correlated well with the corresponding film morphology changes. IrO2 films with the minimum resistivity of （42 ±6）μΩ·cm was obtained at 500℃.