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.     

Effect of substrate biasing and temperature on AlN thin film deposited by cathodic arc ion

Aluminum nitride (AlN) films have been grown in pure N₂ plasma using cathodic arc ion deposition process. The films were prepared at different substrate bias voltages and temperatures. The aim was to investigate their influence on the Al macro-particles, structural and optical properties of deposited films. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning electron microscope (SEM) and Rutherford backscattering spectrometry (RBS) were employed to characterize AlN thin films. XRD patterns indicated the formation of polycrystalline (hexagonal) films with preferential orientation of (002), which is suppressed at higher substrate bias voltage. FTIR and Raman spectroscopic analysis were used to assess the nature of chemical bonding and vibrational phonon modes of AlN thin films respectively. FTIR spectra depicted a dominant peak around 850 cm^?1 corresponding to the longitudinal optical (LO) mode of vibration. A shift in this LO mode peak towards higher wavenumbers was observed with the increase of substrate bias voltage and temperature, showing the upsurge of nitrogen concentration in the deposited film. Raman spectra illustrated a peak at 650 cm^?1 corresponding to E₂ (high) phonon mode depicting the c-axis oriented (perpendicular to substrate) AlN film. SEM analysis showed the AlN film deposited at higher substrate bias voltage contains fewer amounts of Al macro-particles.     

The properties of annealed AlN films deposited by pulsed laser deposition

AlN films deposited on SiC or sapphire substrates by pulsed laser deposition were annealed at 1200°C, 1400°C, and 1600°C for 30 min in an inert atmosphere to examine how their structure, surface morphology, and substrate-film interface are altered during high temperature thermal processing. Shifts in the x-ray rocking curve peaks suggest that annealing increases the film density or relaxes the films and reduces the c-axis Poisson compression. Scanning electron micrographs show that the AlN begins to noticeably evaporate at 1600°C, and the evaporation rate is higher for the films grown on sapphire because the as-deposited film contained more pinholes. Rutherford backscattering spectroscopy shows that the interface between the film and substrate improves with annealing temperature for SiC substrates, but the interface quality for the 1600°C anneal is poorer than it is for the 1400°C anneal when the substrate is sapphire. Transmission electron micrographs show that the as-deposited films on SiC contain many stacking faults, while those annealed at 1600°C have a columnar structure with slightly misoriented grains. The as-deposited films on sapphire have an incoherent interface, and voids are formed at the interface when the samples are annealed at 1600°C. Auger electron spectroscopy shows that virtually no intermixing occurs across the interface, and that the annealed films contain less oxygen than the as-grown films.     

Cubic AlN thin film formation on quartz substrate by pulse laser deposition

Cubic AlN thin films were obtained on quartz substrate by pulse laser deposition in a nitrogen reactive atmosphere. A Nd-YAG laser with a wavelength of 1064 nm was used as the laser source. In order to study the influence of the process parameters on the deposited AlN film, the experiments were performed at various technique parameters of laser energy density from 70 to 260 J/cm², substrate temperature from room temperature to 800℃ and nitrogen pressure from 0.1 to 50 Pa. X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy were applied to characterize the structure and surface morphology of the deposited AlN films. It was found that the structure of AlN films deposited in a vacuum is rocksalt under the condition of substrate temperature 600-800℃, nitrogen pressure 10-0.1 Pa and a moderate laser energy density (190 J/cm²). The high quality AlN film exhibited good optical property.     

Carbon ions irradiation induced modifications in structural and electrical resistivity characteristics of ZrN thin films

Zirconium nitride (ZrN) thin films are irradiated with 800 keV energetic carbon (C) ions in a 5UDH-Pelletron accelerator and the ions irradiation induced effects are investigated. The films are irradiated at various C ions fluences, ranging from 10¹³ to 10¹⁵ ions/cm². The scanning electron microscopy study of the films indicates the development of zirconium (Zr) nanoparticles at ions irradiated region. X-ray diffraction (XRD) patterns of C ions irradiated films also show the formation of (100) and (002) oriented nanocrystalline metallic Zr phases. The irradiated films spectra depict a shift in ZrN peaks towards higher 2θ values, exhibiting that C ions bombardment induces compressive stress in the irradiated films. The appearance of C related peaks in Fourier transform infrared (FTIR) spectra confirms the incorporation of C atoms into ZrN film. Compressive stress has been calculated from the IR peak shift which indicates that higher ion dose (≥5×10¹⁴ ions/cm²) produce lower compressive stress relative to the lower ions fluences. Effect of ion dose on the film resistivity is also reported.     

Effect of electron irradiation on morphological,compositional and electrical properties of nanocluster carbon thin films grown using room temperature based cathodic arc process for large area microelectronics

The influence of 8 MeV electron beam bombardment on room temperature grown nanocluster carbon using cathodic arc process has been studied here. Atomic force microscopy (AFM) study shows that surface roughness varies with varying electron doses. High doses of electrons could causes thermal induce graphitization and morphological changes in the films. Raman spectroscopy analysis reveals that G-peak vary from 1555 cm⁻¹ to 1570 cm⁻¹ and D-peak varying from 1361 cm⁻¹ to 1365 cm⁻¹ indicating the disorderness and presence of both graphitic and diamond-like phases. Room temperature conductivity changes by two to three orders in magnitude. The conductivity in the films could be due to conduction of charge carriers through neighboring islands of conductive chains. Defect states calculated using the differential technique varies from 8 × 10¹⁷cm⁻³ eV⁻¹ to 1.5 × 10¹⁹ cm⁻³ eV⁻¹. Irradiation of nanocluster carbon thin films could be helpful to tune the electrical properties and defect densities of the nanocluster carbon films for various large area, flexible electronic and nano electronic applications.     

Raman scattering of polycrystalline 3C-SiC film deposited on AlN buffer layer by using CVD with HMDS

This paper presents the Raman scattering characteristics of poly (polycrystalline) 3C-SiC thin films deposited on AlN buffer layer by atmospheric pressure chemical vapor deposition (APCVD) using hexamethyldisilane (MHDS) and carrier gases (Ar+H₂). The Raman spectra of SiC films deposited on AlN layer of before and after annealing were investigated according to the growth temperature of 3C-SiC. Two strong Raman peaks, which mean that poly 3C-SiC admixed with nanoparticle graphite, were measured in them. The biaxial stress of poly 3C-SiC/AlN was calculated as 896 MPa from the Raman shifts of 3C-SiC deposited at 1180 °C on AlN of after annealing.     

AlN/GaN/AlN heterostructures grown on Si substrate by plasma-assisted MBE for MSM UV photodetector applications

The AlN/GaN/AlN heterostructures were successfully grown on silicon substrate by plasma-assisted molecular beam epitaxy (MBE). High purity gallium (7N) and aluminum (6N5) were used to grow GaN and AlN, respectively. The structural and optical properties of the samples have been investigated by high-resolution X-ray diffraction (HR-XRD), photoluminescence (PL), Raman spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED), dark field scanning transmission electron microscopy (DF STEM), and high-angle annular dark field scanning transmission electron microscopy (HAADF STEM). HR-XRD measurement showed that the sample has a typical diffraction pattern of hexagonal AlN/GaN/AlN heterostructures. Raman spectra revealed all four Raman-active modes, i.e., GaN-like E₂ (H), AlN-like A₁ (TO), AlN-like E₂ (H), and AlN-like A₁ (LO) inside the AlN/GaN/AlN heterostructures. Good thickness uniformity of the layers and high-quality hetero-structures without cracking were confirmed by TEM, SAED, DF STEM and HAADF STEM. The fabricated AlN/GaN/AlN heterostructures based metal-semiconductor-metal (MSM) for the UV photodetector shows a rise and fall of photoresponses, suggesting that the AlN/GaN/AlN heterostructures have good carrier transport and crystallinity properties.     

纳秒准分子激光合成制备TiN／AlN多层复合膜研究

采用纳秒准分子激光在单晶硅试样表面制备了调制周期为50nm、调制比为2的TiN／AlN多层复合膜,并研究了N2分压对多层膜微结构和硬度的影响。结果表明,在低N2分压下薄膜表面颗粒相对较小,颗粒之间的空隙也不明显;随着N2分压的升高,薄膜表面颗粒明显粗化,且直径变大高度增高,颗粒之间孔隙变大。X射线衍射（XRD）研究表明...     

Influence of Ti film thickness and oxidation temperature on TiO2 thin film formation via thermal oxidation of sputtered Ti film

Single-phase rutile TiO₂ films with good crystallinity were obtained by thermal oxidation of sputtered Ti films on Si and quartz substrates. The influence of the Ti film thickness on oxidation was systematically investigated. A temperature of 823 K was sufficient to fully oxidize Ti films of <0.2 μm in thickness, but 923 K was required for complete oxidation of thicker films. The crystal structure, phase, composition, and optical properties of the TiO₂ films were investigated using X-ray diffraction (XRD), Raman spectroscopy, energy-dispersive X-ray analysis (EDAX), and UV-vis-NIR spectroscopy. XRD and Raman analyses showed that the TiO₂ films are rutile phase. The bandgap of the TiO₂ films decreased with increasing thickness. A growth mechanism for TiO₂ thin films due to thermal oxidation of sputtered Ti films is proposed. Oxidation commences from the surface and proceeds inside the bulk and Ti→TiO₂ phase transformation occurs via different intermediate phases. We found that the oxidation temperature rather than the duration is the dominant factor in the growth of TiO₂ thin films.     

金刚石基底上制备(002)AlN薄膜的研究

首先采用微波等离子体化学气相沉积(MPCVD)方法,在O2/H2/CH4混合气体气氛下利用大功率微波在(100)Si片上生长出了异质外延金刚石膜,X-射线衍射(XRD)、拉曼光谱和场发射扫描电子显微镜(FESEM)对薄膜的表征分析结果表明,制备的金刚石膜具有很高的金刚石相纯度,且晶粒排列紧密;继而采用射频磁控反应溅射法,在抛光的金刚石基底上成功制备了高C轴择优取向的氮化铝(AlN)薄膜,研究了不同的溅射气压、靶基距对AlN薄膜制备的影响,XRD检测结果表明,溅射气压低,靶基距短,有利于AlN(002)面择优取向,相反则更有利于AlN薄膜的(103)面和(102)面择优取向;研究了AlN薄膜在以N终止的金刚石基底和纯净金刚石基底两种表面状态上的生长机制,结果发现,以N终止的金刚石基底非常有利于AlN(002)面择优取向生长;从Al-N化学键的形成以及溅射粒子平均自由程的角度,探讨了其对AlN薄膜择优取向的影响。     

6H-SiC衬底上采用不同厚度AlN缓冲层对GaN外延层的影响

采用不同厚度AlN作为缓冲层在6H-SiC衬底上生长了GaN外延层,并利用X射线衍射,拉曼散射和透射电子显微镜等对GaN性质进行了研究。AlN缓冲层的应变状态对GaN的晶体质量和表面形貌有很大影响。较厚的AlN缓冲层会导致GaN表面出现裂纹,而太薄的AlN缓冲层会导致GaN层较高的位错密度,从而恶化器件性能。分析了GaN产生裂纹和高位错密度的机制,并采用较优厚度（100nm）的AlN缓冲层生长出高质量的GaN外延层。     

AlN薄膜有源SAW滤波器集成及性能研究

在AlN压电薄膜上(以SiO2/Si为衬底),使用MOS集成电路工艺制作叉指电极和单元电路,制成中心频率为320MHz的有源SAW滤波器并进行了测试。结果表明,该滤波器的插入损耗低于10dB,带外衰减高于45dB。     

Characteristics of GaN grown on 6H-SiC with different AlN buffers

Characteristics of GaN grown on 6H-SiC (0001) substrates using different thicknesses of AlN buffers are studied. It is found that the surface morphology and crystal quality of GaN film closely depends on the strain state of the AlN buffer. For a thicker AlN buffer, there are cracks on GaN surface, which make the GaN films unsuitable for applications. While for a thinner AlN buffer, more dislocations are produced in the GaN film, which deteriorates the performance of GaN. Possible generation mechanisms of cracks and more dislocations are investigated and a ～100 nm AlN buffer is suggested to be a better choice for high quality GaN on SiC.     

离子束增强沉积AlN薄膜的研究

利用离子束增强沉积9IBED）法成功地在Si(100）衬底上合成了大面积均匀的非晶AlN薄膜。XRD和XPS测试结果证实该薄膜为非晶且无单质Al和N2存在,随着Al蒸发速率的提高,N/Al下降,在0.05nm/s及0.10nm/s的蒸发速率下制得的薄膜N／Al分别为0.402:1和0.250:1。SRP测试结果表明,随着Al蒸发速率的提高,表面电阻下降,并助在0.05nm/s的速率下制得的薄均匀致密,表面电阻高于10^8Ω,性能良好,而当蒸发速率≥0.25nm/s时,薄膜绝缘性能迅速下降。AFM分析显示薄膜呈岛状分布,且0.05nm/s制取的样品表面呈鹅卵石密堆积,颗粒均匀,表面比0.10nm/s样品起伏平缓、光滑,薄膜的生长机制可能是三维岛状生长。     

c轴择优取向AlN薄膜的制备研究

采用MOCVD法在蓝宝石(0001)单晶衬底上生长AlN压电薄膜。用XRD和原子力显微(AFM)技术表征薄膜的微观结构。研究了衬底温度、TMA和NH3流量、反应室气压对AlN薄膜织构特性的影响,并对薄膜生长的工艺参数进行了相应优化。结果表明:在优化条件下制备的AlN薄膜高度c轴择优取向,(0002)峰摇摆曲线半高宽仅为0.10°,且薄膜表面平整,椭圆偏振法测出其折射率为2.0～2.4。     

MOCVD于高温AlN模板上生长的AlGaN材料

A high temperature AlN template was grown on sapphire substrate by metalorganic chemical vapor deposition.AFM results showed that the root mean square of the surface roughness was just 0.11 nm.Optical transmission spectrum and high resolution X-ray diffraction（XRD）characterization both proved the high quality of the AlN template.The XRD（002）rocking curve full width at half maximum（FWHM）was about 53.7 arcsec and（102）FWHM was about 625 arcsec.The densities of screw threading dislocations（TDs）and edge TDs wereestimated to be - 6 × 10^6 cm^-2 and - 4.7 ×10^9 cm^-2. AlGaN of Al composition 80.2% was further grown on the AlN template. The RMS of the surface roughness was about 0.51 nm. XRD reciprocal space mapping was carried out to accurately determine the Al composition and relaxation status in the AlGaN epilayer. The XRD （002） rocking curve FWHM of the AIGaN epilayer was about 140 arcsec and （102） FWHM was about 537 arcsec. The density of screw TDs was estimated to be - 4 × 10^7 cm^-2 and that of edge TDs was - 3.3 × 10^9 cm^-2. These values all prove the high quality of the AlN template and AlGaN epilayer.     

Effects of Cu incorporation on physical properties of ZnTe thin films deposited by thermal evaporation

The present paper reports on a systematic study of the Cu doping effect on the optical, electrical and structural properties of ZnTe:Cu (Cu=0, 6, 8, and 10 at%) thin films. Polycrystalline Cu-doped ZnTe thin films were deposited on glass substrates at room temperature by thermal evaporation. A detailed characterization of the Cu-doped ZnTe films were performed by X-ray diffraction (XRD), Spectrophotometry, Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. XRD of the as-deposited Cu-doped ZnTe films belong to single-phase cubic structure of ZnTe with preferential orientation along (111) planes revealed minor effect of Cu content. The interference pattern in optical transmission spectra was analyzed to determine energy band gap, refractive index, extinction coefficient and thickness of the films. Wemple–DiDomenico and Tauc's relation were used for the determination and comparison of optical band gap values. The formation of ZnTe and Cu-doped ZnTe phase was confirmed by FT-IR. AC conductivity in a frequency range of 0–7 MHz has been studied for investigation of the carriers hoping dynamics in the films. Raman spectra indicated merely typical longitudinal optical (LO) phonon mode of the cubic structure ZnTe thin film at 194 cm⁻¹ because the excitation energy is well above of the optical band-gap of the material and exhibited a blue-shift from 194 to 203 cm⁻¹ with Cu which could be associated to the substitution of Zn atom with Cu at the lattice sites.     

The significant effect of film thickness on the properties of chalcopyrite thin absorbing films deposited by RF magnetron sputtering

In this paper, thickness dependent structural, surface morphological, optical and electrical properties of RF magnetron sputtered CuIn_0.8Ga_0.2Se₂ (CIGS) thin films were studied using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FE-SEM), Atomic force microscopy (AFM), UV–vis–NIR spectrophotometer and Keithley electrical measurement unit. The peak intensity along (112) plane as well as crystallite size was found to increase with thickness. However, for higher film thickness >1.16 μm, crystallinity reduced due to higher % of Cu content. TEM analysis confirmed pollycrysallinity as well as chalcopyrite phase of deposited films. The band gap was found to decrease with increase in thickness yielding a minimum value of 1.12 eV for film thickness 1.70 μm. The I–V characteristics showed the ohmic behavior of metal semiconductor contact with higher conductivity for film thickness 1.16 μm.     

磁过滤阴极真空弧沉积薄膜研究

采用磁过滤阴极真空弧沉积技术对从弧源引起离子束中的大颗粒进行过滤后,在硅和聚合物表面进行离子注入和低能离子束沉积,可获得特性优异的沉积金属膜、超硬膜（类金刚石,CN膜）、陶瓷膜（TiN,TiC）等。电子显微镜观察表明,大颗粒已被过滤,表面结构致密,由于先进行离子注入,在基体表现预先形成了过滤层,从而改善了沉积膜的粘合特性,膜与基体的粘合特性有了明显提高。测量结果表明,沉积膜的硬度、抗磨损和抗腐蚀特性均有了明显提高。非晶金刚石薄膜表面硬度可达到56GPa。