Structural and chemical characterization of as-deposited microcrystalline indium oxide films prepared by dc reactive magnetron sputtering

Microcrystalline indium oxide (InO_x) films with thickness of 120–1600 nm were prepared by dc reactive magnetron sputtering in various mixtures of oxygen in argon at room temperature. The depositions were carried out onto Corning 7059 glass and silicon substrates. The conductivity of the as-deposited films can change in a controllable and fully reversible manner by about six orders of magnitude by alternately exposing the films to ultraviolet (UV) light (hv≥3.5eV) in vacuum and reoxidizing them in ozone. The microstructure of the films was investigated using transmission electron microscopy (TEM) and electron diffraction. For this purpose, films with a thickness of about 100 nm were deposited onto NaCl substrates. The surface and depth composition of the films were examined using Auger electron spectroscopy (AES) combined with depth profiling analysis. The depth profiles showed that all the films exhibit an extremely good in-depth uniformity, all the way to the interface with the glass substrate, regardless of their thickness. Quantitative Auger and energy dispersive x-ray (EDX) analyses were employed to determine the stoichiometry of the films. An oxygen deficiency of 2–5% has been observed with respect to the stoichiometric composition. The effects of film thickness and oxygen content in the sputtering gas on the stoichiometry were examined. Both AES and EDX analyses confirmed that the stoichiometry is invariant for these parameters.     

Electrical characterization and morphological properties of AlN films prepared by dc reactive magnetron sputtering

Aluminum nitride (AlN) films were deposited by dc reactive magnetron sputtering on p-Si-(1 0 0) substrate in Ar-N₂ gas mixtures. The effects of nitrogen concentration and sputtering power on AlN films deposition rate, crystallographic orientation, refractive index, and surface morphology are investigated by means of several characterization techniques. The results show that AlN films reasonably textured in (0 0 2) orientation with low surface roughness can be obtained with the deposition rate as high as 70 nm/min by the control of either target power or N₂ concentration in the gas mixture. Increasing the dc discharge power, Al atoms are not completely nitridized and the Al phases appear, as well as the AlN phases. MIS (Metal-Insulator-Semiconductor) structures were fabricated and electrically evaluated by I-V (current-voltage) and C-V (capacitance-voltage) measurements at high frequency (1 MHz). The results obtained from C-V curves indicate that charges at the dielectric/semiconductor interface occur, and the dielectric constant values (extracted under strong accumulation region) are compatible with those found in literature.     

Studies of yttrium oxide films prepared by RF magnetron sputtering

Films of yttrium oxide (Y₂O₃) were deposited on Si substrates from a Y₂O₃ target by RF magnetron sputtering. MIS capacitors in the form of Al and Y₂O₃ (400 Å)-Si were then fabricated. The leakage current density was about 10^-6 A/cm² at 1.3×10⁶ V/cm, and the breakdown field of the films was about 2.75×10⁶ V/cm. The dielectric constant of the sputtered Y₂O₃ was found to be about 12-12.7     

Low-temperature deposition of silicon oxide and silicon nitride by reactive magnetron sputtering

In this study, oxide and nitride films were deposited at room temperature through the reaction of silicon sputtered by argon and oxygen ions or argon and nitrogen ions at 250 and 350 W with 0.67 Pa pressure. It was observed that for both thin films the deposition rates increase with the applied RF power and decrease with the increase of the gas concentration. The Si/O and Si/N ratio were obtained through RBS analyses and for silicon oxide the values changed from 0.42 to 0.57 and for silicon nitride the values changed from 0.4 to 1.03. The dielectric constants were calculated through capacitance-voltage curves with the silicon oxide values varying from 2.4 to 5.5, and silicon nitride values varying from 6.2 to 6.7, which are good options for microelectronic dielectrics.     

Preparation and characteristics of Nb-doped indium tin oxide thin films by RF magnetron sputtering

Niobium-doped indium tin oxide(ITO:Nb)thin films are fabricated on glass substrates by radio frequency(RF)magnetron sputtering at different temperatures.Structural,electrical and optical properties of the films are investigated using X-ray diffraction(XRD),atomic force microscopy(AFM),ultraviolet-visible(UV-VIS)spectroscopy and electrical measurements.XRD patterns show that the preferential orientation of polycrystalline structure changes from(400)to(222)crystal plane,and the crystallite size increases with the increase of substrate temperature.AFM analyses reveal that the film is very smooth at low temperature.The root mean square(RMS)roughness and the average roughness are 2.16 nm and 1.64 nm,respectively.The obtained lowest resistivity of the films is 1.2×10-4?.cm,and the resistivity decreases with the increase of substrate temperature.The highest Hall mobility and carrier concentration are 16.5 cm2/V.s and 1.88×1021 cm-3,respectively.Band gap energy of the films depends on substrate temperature,which is varied from 3.49 eV to 3.63 eV.     

A study on phase transformation of SnOx thin films prepared by reactive magnetron sputtering

In the paper, SnO_x thin films were deposited by reactive magnetron sputtering from a tin target in O₂ containing working gas. The evolution from Sn-containing SnO to tetravalent SnO₂ films was investigated. The films could be classified into three groups according to their optical band gaps, which are E_g<2.5 eV, E_g=3.0–3.3 eV and E_g>3.7 eV. The electric measurements show that high conductivity can be obtained much easier in SnO₂ than in SnO films. A high electron mobility of 15.7 cm² V⁻¹ s⁻¹, a carrier concentration of 1.43×10²⁰ cm⁻³ and a resistivity of 2.8×10⁻³ Ω cm have been achieved in amorphous SnO₂ films. Films with the optical band gap of 3.0–3.3 eV remain amorphous though the substrate temperature is as high as 300 °C, which implies that °btaining high mobility in p-type SnO is more challenging in contrast to n-type SnO₂ films.     

磁控溅射技术制备织构化表面Al掺杂ZnO薄膜

以Zn-Al(Al:2wt.%)合金为溅射靶材,采用直流反应磁控溅射的方法,在普通玻璃衬底上制备Al掺杂ZnO(AZO)薄膜。通过对衬底温度的调制,在较高衬底温度下(～280℃),无需经过常规溅射后腐蚀工艺过程,即可获得表面形貌具有特征陷光结构的AZO薄膜,其表面呈现"类金字塔"状,粗糙度RMS=65.831nm。通过测试薄膜的结构特性、表面形貌及其光电性能,详细地研究了衬底温度对AZO薄膜性能的影响。X射线衍射(XRD)和扫描电子显微镜(SEM)测试表明,所有样品均为多晶六角纤锌矿结构,薄膜呈(002)晶面择优生长,其表面形貌随衬底温度的不同而改变。衬底温度为200℃及其以上工艺条件下获得的AZO薄膜,在可见光及近红外范围的平均透过率大于90%,电阻率优于1.5×10-3Ωcm。     

Deposition and characterization of indium oxide and indium tin oxide semiconducting thin films by reactive thermal deposition technique

In this paper, the deposition conditions and the characterization properties of the indium oxide (10) and indium tin oxide (ITO) thin films deposited by a reactive thermal deposition technique using the indium, indium-tin alloy sources are reported. The actively involved parameters during deposition have been identified for various substrate temperatures. The effect of oxygen partial pressure in evaporation has been identified. The indium-tin alloy source which was used in this work was prepared by hot zone diffusion technique. The structural, optical, and electrical properties have been characterized using optical microscope, x-ray diffractometer, ultraviolet spectrophotometer, and Hall effect measurement setup. The uniformity of the deposited films and the uniformity of the substrate surface effect on the deposited thin films were analyzed through sheet resistance measurements. The depositions were carried out on glass and quartz substrates. Good optical transmittance (99%) was achieved for 740 nm wavelength and above. The absorbance spectrum exhibit a value of 2% absorbance for IO/quartz structures. Large area (5.0 × 3.8 cm) film with unique optical properties is also reported here.     

透明导电薄膜ZnO:Zr的反应磁控溅射法制备及表征

以Zn金属靶和Zr金属片组成的Zn:Zr为靶材,利用直流反应磁控溅射法在玻璃衬底上制备ZnO:Zr透明导电薄膜。研究了靶与衬底之间的距离对所制备薄膜结构和性能的影响。实验制备的ZnO:Zr薄膜为六方纤锌矿结构的多晶薄膜,且具有与衬底方向垂直的c轴择优取向。实验结果表明,靶与衬底之间的距离对ZnO:Zr薄膜的结构、生长速率、密度及电学性能有很大影响。靶与衬底之间的最佳距离为6.0cm,在此条件下制备的ZnO:Zr薄膜具有最小电阻率1.78×10-3Ω.cm,其可见光透过率为88.5%,折射率为2.04。     

Ta/Si Schottky diodes fabricated by magnetron sputtering technique

Electrical properties of Ta/n-Si and Ta/p-Si Schottky barrier diodes obtained by sputtering of tantalum (Ta) metal on semiconductors have been investigated. The characteristic parameters of these contacts like barrier height, ideality factor and series resistance have been calculated using current voltage (I-V) measurements. It has seen that the diodes have ideality factors more than unity and the sum of their barrier heights is 1.21 eV which is higher than the band gap of the silicon (1.12 eV). The results have been attributed the effects of inhomogeneities at the interface of the devices and native oxide layer. In addition, the barrier height values determined using capacitance-voltage (C-V) measurements have been compared the ones obtained from I-V measurements. It has seen that the interface states have strong effects on electrical properties of the diodes such as C-V and R_s-V measurements.     

Electronic properties of zinc oxide thin films prepared by RF magnetron sputtering for varistor applications

ZnO thin films for varistor applications have been prepared by RF magnetron sputtering at a power of 0-1 kW using an argon pressure of 05 Pa. The films were polycrystalline with mean grain size typically 13 nm, and were preferentially oriented in the [002] direction. Optical absorption studies revealed a fundamental absorption edge at a wavelength of approximately 360 nm with a direct bandgap of 3.36 eV. van der Pauw measurements showed a decrease in resistivity from approximately 12ωm at thickness 50 nm to 0-5 ωm at thickness greater than 500 nm. Below 350 K the resistivity was essentially constant, while at higher temperatures an activation energy of approximately 0-2eV was observed, which was attributed to the effects of oxygen vacancies.     

溅射压强对磁控溅射法制备的ZnO:Zr透明导电薄膜性能的影响

Transparent conducting zirconium-doped zinc oxide films with high transparency and relatively low resistivity have been successfully prepared on water-cooled glass substrate by radio frequency magnetron sputtering at room temperature. The Ar sputtering pressure was varied from 0.5 to 3 Pa. The crystallinity increases and the electrical resistivity decreases when the sputtering pressure increases from 0.5 to 2.5 Pa. The cystallinity decreases and the electrical resistivity increases when the sputtering pressure increases from 2.5 to 3 Pa. When the sputtering pressure is 2.5 Pa, it is obtained that the lowest resistivity is 2.03 x 10^-3Ω .cm with a very high transmittance of above 94%. The deposited films are polycrystalline with a hexagonal structure and a preferred orientation perpendicular to the substrate.     

Effect of thickness on optoelectrical properties of Nb-doped indium tin oxide thin films deposited by RF magnetron sputtering

Niobium-doped indium tin oxide （ITO:Nb） thin films are prepared on glass substrates with various film thicknesses by radio frequency （RF） magnetron sputtering from one piece of ceramic target material. The effects of thickness （60-360 nm） on the structural, electrical and optical properties of ITO: Nb films are investigated by means of X-ray diffraction （XRD）, ultraviolet （UV）-visible spectroscopy, and electrical measurements. XRD patterns show the highly oriented （400） direction. The lowest resistivity of the films without any heat treatment is 3.1×10^-4 Ω·cm^-1, and the resistivity decreases with the increase of substrate temperature. The highest Hall mobility and carrier concentration are 17.6 N·S and 1.36×10²¹ cm^-3, respectively. Band gap energy of the films depends on substrate temperature, which varies from 3.48 eV to 3.62 eV.     

衬底温度对反应溅射TiN_x薄膜结构与电阻率的影响

采用反应磁控溅射方法,在不同Si(100)衬底温度下,制备出了TiNx薄膜。通过X射线衍射(XRD)、扫描电子显微镜(SEM)对TiNx薄膜的物相、微观结构进行了表征,采用电子能谱仪(EDS)测定了TiNx薄膜的成分,运用四探针测试仪测量了TiNx薄膜的电阻率,研究了衬底温度对溅射TiNx薄膜结构与电阻率的影响。研究结果表明:衬底温度从室温升高到600℃时,随着温度升高,TiNx薄膜的(111)晶面衍射峰逐渐增强,500℃后减弱;(200)晶面衍射峰在300℃时最强,之后减弱。随着衬底温度的升高,TiNx薄膜的晶粒逐渐增大,300℃达最大后减小。随着衬底温度升高,TiNx薄膜的N/Ti原子含量比降低,200℃时降到最低为0.99,随后升高,500℃时最高为1.34,随后再次降低。N/Ti原子含量比与薄膜电阻率呈明显反比变化。     

Influence of the sputtering pressure on the properties of transparent conducting zirconium-doped zinc oxide films prepared by RF magnetron sputtering

Transparent conducting zirconium-doped zinc oxide films with high transparency and relatively low re-sistivity have been successfully prepared on water-cooled glass substrate by radio frequency magnetron sputtering at room temperature. The Ar sputtering pressure was varied from 0.5 to 3 Pa. The crystallinity increases and the electri-cal resistivity decreases when the sputtering pressure increases from 0.5 to 2.5 Pa. The cystallinity decreases and the electrical resistivity increases when the sputtering pressure increases from 2.5 to 3 Pa. When the sputtering pressure The deposited films are polycrystalline with a hexagonal structure and a preferred orientation perpendicular to the substrate.     

Au schottky barrier diodes on β-SiC thin films deposited on silicon substrates by reactive magnetron sputtering technique

β-SiC thin films have been grown on (100) silicon substrates using reactive magnetron sputtering of a silicon target in an Ar/CH₄ mixed plasma. For the first time it has been possible to make gold Schottky diodes on β-SiC grown by reactive magnetron sputtering. Current-voltage measurements showed an ideality factor of 1.27 and a leakage current density of 4 μA/cm². Capacitance-voltage measurements gave a barrier height of 1.04 eV. The static dielectric constant for β-SiC was determined to be 9.     

Bias voltage dependence properties of Nb-doped indium tin oxide thin films by RF magnetron sputtering at room temperature

Niobium doped indium tin oxide (ITO:Nb) thin films were fabricated on glass substrates by RF magnetron sputtering from one piece of ceramic target material at room temperature. The bias voltage dependence of properties of the ITO:Nb films were investigated by adjusting the bias voltage. Structural, electrical and optical properties of the films were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), UV–visible spectroscopy, and electrical measurements. XRD patterns showed a change in the preferential orientations of polycrystalline crystalline structure from (222) to (400) crystal plane with the increase of negative bias voltage. AFM analysis revealed that the smooth film was obtained at a negative bias voltage of -120 V. The root mean square (RMS) roughness and the average roughness are 1.37 nm and 1.77 nm, respectively. The films with the lowest resistivity as low as 1.45×10⁻⁴ Ω cm and transmittance over 88% have been obtained at a negative bias voltage of −120 V. Band gap energy of the films, depends on substrate temperature, varied from 3.56 eV to 3.62 eV.     

Different properties of aluminum doped zinc oxide nanostructured thin films prepared by radio frequency magnetron sputtering

Aluminium doped zinc oxide (AZO) nanostructured thin films are prepared by radio frequency magnetron sputtering on glass substrate using specifically designed ZnO target containing different amount of Al₂O₃ powder as the Al doping source. The optical properties of the aluminium doped zinc oxide films are investigated. The topography of the deposited films were investigated by Atomic Force Microscopy. Variation of the refractive index by annealing temperature are considered and it is seen that the refractive index increases by increasing the annealing temperature.     

Nitridation of hafnium oxide by reactive sputtering

Hafnium oxide films were RF sputtered from HfO₂ target in Ar/O₂ or Ar/N₂ ambient on silicon substrates. The composition of the deposited films was analyzed by X-ray photoelectron spectroscopy (XPS). For samples sputtered in Ar/N₂, it was observed that nitrogen was incorporated in the bulk of hafnium oxide films in the form of HfON, and SiON layer was formed at the silicon-insulator interface. After annealing the hafnium oxide films at 600-700 °C, MOS structures were fabricated and used for electrical characterization. The effects of nitridation of hafnium oxide on both the capacitance-voltage and current-voltage characteristics of the MOS capacitors were discussed.