室温制备低电阻率高透过率H,W共掺杂ZnO薄膜

采用脉冲直流磁控溅射法,以WO3:ZnO陶瓷靶为溅射靶材,通过在溅射气氛中引入H2的方式,在室温条件下制备了低电阻率、高可见和近红外光区透过率的H,W共掺杂ZnO (HWZO)薄膜.系统地研究了H2流量对所制备的HWZO薄膜的结构、组分、元素价态、光电特性的影响.结果表明:掺入的H可促进Zn的氧化,改善薄膜的结晶质量,提高薄膜透过率.H引入之后薄膜的载流子浓度增加,电阻率降低.在H2流量为6mL/min时制备的HWZO薄膜性能最优,电阻率为7.71×10-4 Ω·m,光学带隙为3.58 eV,400-1100 nm的平均透过率为82.4％.     

Ni掺杂ZnO薄膜的结构与光学特性研究

使用射频磁控溅射法成功制备了不同掺杂浓度（0—7at.%）的ZnO:Ni薄膜.X射线衍射的θ-2θ和摇摆曲线扫描结果表明,5at.%Ni掺杂ZnO薄膜具有沿c轴方向最佳的择优取向生长特性,（002）衍射峰向大角度方向移动揭示了Ni杂质被掺入ZnO晶格中占据Zn位.ZnO:Ni薄膜具有较好的可见光透明特性,拟合发现薄膜的光学带隙随Ni掺杂量的增加由3.272 eV线性降低到3.253 eV.未掺杂薄膜在550 nm处呈现出一个绿色发光峰,掺入Ni杂质后薄膜主要表现了以430 nm为中心的蓝色发光,分析认为它们分别源于薄膜中O空位和Zn填隙缺陷发光. 关键词： ZnO:Ni薄膜 结构特性 光学带隙 光致发光     

ZnO薄膜的掺杂特性

通过MOCVD方法生长的ZnO薄膜一般为富锌生长,呈n型电导,要想得到高阻或低阻p-ZnO薄膜需要对其进行掺杂施主或受主杂质.主要研究在生长过程中通过NH₃对ZnO薄膜进行氮掺杂的情况,利用优化生长条件,即生长温度为610℃,Ar气(携带DEZn)流量为4sccm,O₂流量为120sccm,N₂流量为600sccm,得到在NH₃流量为80sccm时生长样品的结晶质量最高,在掺杂薄膜中NH₃流量高于或低于80sccm时,样品的表面形貌都将变差,只有在80sccm时表面粗糙度最低晶粒最小,表明该流量下获得的样品表面较光滑致密.所以80sccmNH₃流量为在R面蓝宝石上生长<110>取向ZnO薄膜的最佳掺杂流量.Hall测量结果表明,NH₃流量为50sccm的样品电导呈弱p型,电阻率为102Ω·cm,空穴载流子浓度为+1.69×10¹⁶cm^-3,迁移率为3.6cm²·V^-1·s^-1;当NH₃流量增加时样品的电导呈n型,电阻率最高达10⁸Ω·cm,我们认为与进入ZnO薄膜的H的量有关,并对其变化机理进行了详细的分析.     

白宝石衬底上生长的MgxZn1-xO晶体薄膜的结构和光学性能

在白宝石 (sapphire)衬底上低温外延生长出了MgxZn1 -xO晶体薄膜 .x射线衍射 (XRD)及能量色散x射线 (EDX)分析表明 ,MgxZn1 -xO薄膜的晶体结构依赖于薄膜中Mg的组分x,随着Mg组分的增大 ,MgxZn1 -xO薄膜的结构从与ZnO晶体一致的六方结构转变为与MgO晶体一致的立方结构 .对MgxZn1 -xO薄膜的紫外透射光谱及紫外光致荧光谱 (UVPL)的分析表明 ,随着Mg组分的增大 ,光学吸收边产生明显的蓝移 ,表明MgxZn1 -xO晶体薄膜的带隙增大 ,且带隙连续可调 .吸收光谱和XRD测量显示 ,带隙高达 5 6 5eV的MgxZn1 -xO晶体薄膜与MgO之间的晶格失配仅为0 16 % .     

溅射制备Ge,Nb共掺杂窄光学带隙和低电阻率的TiO2薄膜

采用射频磁控溅射技术制备了Ge,Nb共掺杂的锐钛矿结构TiO₂薄膜,详细探讨了薄膜的结构、电阻率及光学带隙等性质随Ge,Nb掺杂量、溅射功率和热处理温度等参数的变化,发现Ge,Nb共掺杂可以同时调节TiO₂薄膜的光学带隙和电阻率.体积分数约为6%Nb和20%Ge的共掺杂TiO₂薄膜电阻率由10⁴Ω/cm减小至10^-1Ω/cm,光学带隙由3.2 eV减小至1.9 eV.退火后掺杂TiO₂薄膜不仅显示更低的电阻率,还表现出更强的可见-红外光吸收.结果表明,改变Ge,Nb的掺杂量和退火条件能够制备出电阻率和带隙都可调的TiO₂薄膜.     

微量Mg掺杂ZnO薄膜的光致发光光谱和带隙变化机理研究

利用射频磁控溅射(RF-MS)法在450℃玻璃基底上制备了Mg掺杂量分别为0.81at%,2.43at%和4.05at%的ZnO薄膜,对其微观结构、室温光致发光光谱(PL)、光学和电学性质进行了研究.结果发现,微量Mg掺杂ZnO薄膜晶体具有六方纤锌矿结构并保持高结晶质量;掺杂0.81at%和2.43at%Mg的ZnO薄膜室温PL谱中近带边发射(NBE)峰的短波方向出现了高能发射带与NBE峰同时存在;随着Mg掺杂量增加至4.05at%,这个高能发射带逐步将NBE峰掩盖.推测在Mg掺杂ZnO薄膜中,Mg2+替代Zn2+附近核外电子的能量增大并产生了一个高能级.而未被Mg2+替代的Zn2+周围的核外电子能量状态不变,带间能级依然存在,随着Mg掺杂量的增加处于高能级的电子数目逐步增加并占绝对优势.因此,ZnO薄膜随着Mg掺杂量增加薄膜禁带宽度增大,这是由于Mg掺杂后周围电子能量增大与Burstein-Moss效应共同作用的结果.另外,薄膜在可见光区域的平均透射率均大于85%,随着Mg掺杂量的增加,薄膜禁带宽度增大并在3.36—3.52eV内变化;Mg掺杂量为0.81at%,2.43at%和4.05at%时,薄膜电阻率分别为2.2×10-3,3.4×10-3和8.1×10-3Ω.cm.     

W掺杂ZnO透明导电薄膜的理论及实验研究

本文从理论与实验两方面入手, 对高价态差金属W掺杂ZnO (WZO) 薄膜材料的特性进行分析讨论. 采用基于密度泛函理论的平面波赝势方法对WZO材料特性进行理论分析, 计算结果表明: W以替位形式掺入ZnO六角纤锌矿晶格结构中, 由于W-O键的键长较长引起晶格常数增加, 产生晶格畸变; 掺杂后费米能级进入导带, 其附近的导电电子主要由W 5d, O 2p及Zn 3d电子轨道提供, 材料表现出n型半导体的特性; 同时能带简并效应使其光学带隙展宽. 为进一步验证该理论分析结果的适用性, 本文采用脉冲直流磁控溅射技术进行了本征ZnO及WZO薄膜的实验研究, 结果表明: W掺入未改变ZnO的生长方式, 但引起薄膜的晶格常数增加, 电阻率由本征ZnO的1.35× 10^-2 Ω·cm减小到1.55× 10^-3 Ω·cm, 光学带隙由3.27 eV展宽到3.48 eV. 制备的WZO薄膜在400-1100 nm的平均透过率大于83%. 实验结果对理论计算结果进行了验证, 表明WZO薄膜作为透明导电薄膜的应用潜力.     

氟化非晶碳薄膜的光学带隙分析

研究了CHF3C6H6沉积的氟化非晶碳(αC∶F)薄膜的光学带隙.发现αC∶F薄膜光学带隙的大小取决于薄膜中C—F,CC的相对含量.这是由于CC形成的窄带隙π键和C—F形成的宽带隙σ键含量的相对变化,改变了带边态密度分布的结果.在微波功率为140—700W、沉积气压为01—10Pa、源气体CHF3∶C6H6流量比为1∶1—10∶1条件下沉积的αC∶F薄膜,光学带隙在176—398eV之间 关键词： 氟化非晶碳(αC∶F)薄膜 光学带隙 键结构     

电子回旋共振等离子体增强沉积氟化非晶碳薄膜的光学性质

用紫外可见光透射光谱(UV-VIS)并结合键结构的X射线光电子能谱(XPS)和红外谱(FTIR)分析,研究了电子回旋共振等离子体增强化学气相沉积法制备的氟化非晶碳薄膜的光吸收和光学带隙性质.在微波功率为140—700W、源气体CHF₃∶C₆H₆比例为1∶1—10∶1条件下沉积的薄膜,光学带隙在1.76—2.85eV之间.薄膜中氟的引入对吸收边和光学带隙产生较大的影响,吸收边随氟含量的提高而增大,光学带隙则主要取决于CF键的含量,是由于强电负 关键词： 氟化非晶碳薄膜 光吸收与光学带隙 电子回旋共振等离子体     

Ga-Ti共掺杂ZnO薄膜的制备及其光电性能

采用ZnO:Ga2O3:TiO2为靶材,在玻璃衬底上射频磁控溅射制备了多晶Ga-Ti共掺杂ZnO(GTZO)薄膜,通过XRD、四探针、透射光谱测试研究了生长温度对薄膜结构和光电性能的影响.结果表明:所制备的薄膜具有c轴择优取向,光学带隙均大于本征ZnO的禁带宽度.当生长温度为620K时GTZO薄膜的结晶质量最佳、电阻率最低、透射率最大、品质因数最高.     

Electrical and optical properties of reactive dc magnetron sputtered silver-doped indium oxide thin films: role of oxygen

Silver-doped indium oxide thin films have been prepared on glass and quartz substrates at room temperature (300 K) by a reactive dc magnetron sputtering technique using an alloy target of pure indium and silver (80:20 at. %). During sputtering, the oxygen flow rates are varied in the range 0.00–2.86 sccm keeping the magnetron power constant at 40 W. The resistivity of these films is in the range 10⁰–10^-3 Ω cm and they show a negative temperature coefficient of resistivity. The films exhibit p-type conductivity at an oxygen flow rate of 1.71 sccm. The work function of these silver–indium oxide films has been measured by a Kelvin probe technique. The refractive index of the films (at 632.8 nm) varies in the range 1.13–1.20. Silver doping in indium oxide narrows the band gap of indium oxide (3.75 eV). PACS 73.30.+y; 81.15.Cd; 78.20.Ci; 73.61.Le     

微波ECR磁控溅射制备SiNx薄膜的XPS结构研究

利用微波电子回旋共振等离子体增强非平衡磁控溅射法在不同N₂流量下制备无氢SiN_x薄膜.通过X光电子能谱、纳米硬度仪等表征技术,研究了不同N₂流量下制备的SiN_x薄膜的化学键结构、化学键含量、元素配比及各元素沿深度分布.研究结果表明,N₂流量是影响SiN_x薄膜化学键结构、元素配比、元素延深度分布等性质的主要因素.在N_{2关键词： x}')" href="#">SiN_x 磁控溅射 XPS 化学键结构     

沉积参数对SiNx薄膜结构及阻透性能的影响

利用直流脉冲磁控溅射法在室温下制备无氢SiN_x薄膜.通过傅里叶变换红外光谱、台阶仪、紫外—可见分光光度计、接触角测量仪、透湿测试仪等表征技术,分析了N₂流量、Si靶溅射功率等实验参数对SiN_x薄膜成分、结构、及阻透性能、透光性能、接触角等性能的影响.研究结果表明,Si靶溅射功率固定时,在低N₂流量条件下,或N₂流量固定时,在高Si靶溅射功率条件下,制备的SiN _{关键词： x}')" href="#">SiN_x 磁控溅射 微观结构 阻透性能     

Effect of balanced and unbalanced magnetron sputtering processes on the properties of SnO2 thin films

A comparative study has been carried on the role of balanced magnetron (BM) and unbalanced magnetron (UBM) sputtering processes on the properties of SnO₂ thin films. The oxygen partial pressure, substrate temperature and deposition pressure were kept 20%, 700 °C and 30 mTorr, respectively and the applied RF power varied in the range of 150–250 W. It is observed that the UBM deposition causes significant effect on the structural, electrical and optical properties of SnO₂ thin films than BM as evidenced by X-ray diffraction, C-V, Spectroscopic Ellipsometer and Photoluminescence measurements. The value of band gap (E_g) of the films deposited at 150 W in UBM is found as E_g = 3.83 eV which is much higher than the value of E_g = 3.69 eV as observed in BM sputtering indicating that UBM sputtering results in good crystalline quality. Further, the C-V measurements of SnO₂ thin films deposited using UBM at high power 250 W show hysteresis with large flat band shift indicating that these thin films can be used for the fabrication of memory device. The observed results have been attributed to different mechanisms which exist simultaneously under unbalanced magnetron sputtering due to ion bombardment of growing SnO₂ thin film by energetic Ar+ ions.     

Optical and mechanical properties of AlF3 films produced by pulse magnetron sputtering of Al targets with CF4/O2 gas

In this study, AlF₃ thin films were deposited by pulse magnetron sputtering of Al targets with different ratios of CF₄/O₂ gas and at different sputtering powers. The optical and mechanical properties of the AlF₃ thin films were analyzed. The transmittance spectra showed no obvious negative inhomogeneous refractive indices. Denser films with a low optical absorption were obtained when high sputtering powers were used (larger than 30 W). The lowest extinction coefficient (7.3 × 10⁻⁴ at 193 nm) of the films can be reached with 12 sccm O₂ flow rate and at 160W sputtering power. All of the residual stresses were compressive and their trends were consistent with the refractive indices. The lowest compressive stress (0.068 GPa) was obtained when the AlF₃ films were prepared at 160W sputtering power.     

Synthesis and characterization of Zn(O,OH)S and AgInS2 layers to be used in thin film solar cells

In this paper AgInS₂ and Zn(O,OH)S thin films were synthesized and characterized. AgInS₂ layers were grown by co-evaporation from metal precursors in a two-step process, and, Zn(O,OH)S thin films were deposited from chemical bath containing thiourea, zinc acetate, sodium citrate and ammonia. X-ray diffraction measurements indicated that AgInS₂ thin films grown with chalcopyrite structure, and the as-grown Zn(O,OH)S thin films were polycrystalline. It was also found that the AgInS₂ films presented p-type conductivity, a high absorption coefficient (greater than 10⁴ cm⁻¹) and energy band-gap E_g of about 1.95 eV, Zn(O,OH),S thin films presented E_g of about 3.89 eV. Morphological analysis showed that under this synthesis conditions Zn(O,OH),S thin films coated uniformly the absorber layer. Additionally, the Zn(O,OH)S kinetic growth on AgInS₂ layer was studied also. Finally, the results suggest that these layers possibly could be used in one-junction solar cells and/or as top cell in a tandem solar cell.     

Effect of H2 dilution on a-CN:H films deposited by hot-wire chemical vapor deposition

Hydrogenated amorphous carbon nitride (a-CN:H) thin films were deposited by hot-wire chemical vapor deposition (HWCVD) using the gas mixture of CH₄, NH₃ and H₂ precursor gases. The structural and electronic environments studies of H₂ diluted a-CN:H films were carried out by Raman spectroscopy and X-ray photoelectron spectroscopy. The nitrogen content increases while the total carbon contents decreases with increase in H₂ flow rate from 0 sccm to 20 sccm in the a-CN:H films. Moreover, the detail analysis of the carbon core orbital, valence band and hole states of a-CN:H were discussed with different H₂ flow rate.     

Synthesis and characterization of electron beam evaporated LiCoO<Subscript>2</Subscript> thin films

LiCoO₂ thin films were prepared by electron beam evaporation technique using LiCoO₂ target with Li/Co ratio 1.1 in an oxygen partial pressure of 5 × 10⁻⁴ mbar. The films prepared at substrate temperature T _s < 573 K were amorphous in nature, and the films prepared at T _s > 573 K exhibited well defined (104), (101), and (003) peaks among which the (104) orientation predominates. The X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma (ICP) data revealed that the films prepared in the substrate temperature range 673–773 K are nearly stoichiometric. The grain size increases with an increase of substrate temperature. The Co–e_g absorption bands, are empty and their peak position lies at around 1.7 eV above the top to the Co–t_2g bands. The fundamental absorption edge was observed at 2.32 eV. The films annealed at 1,023 K in a controlled oxygen environment exhibit (104) out plane texture with large grains. Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006     

Structural and optoelectronic properties of amorphous GaN thin films

Amorphous gallium nitride (a-GaN) thin films were deposited on glass substrate by electron beam evaporation technique at room temperature and high vacuum using N ₂ as carrier gas. The structural properties of the films was studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). It was clear from XRD spectra and SEM study that the GaN thin films were amorphous. The absorbance, transmittance and reflectance spectra of these films were measured in the wavelength range of 300–2200 nm. The absorption coefficient spectral analysis in the sharp absorption region revealed a direct band gap of E _g = 3:1 eV. The data analysis allowed the determination of the dispersive optical parameters by calculating the refractive index. The oscillator energy E ₀ and the dispersion energy E _d, which is a measure of the average strength of inter-band optical transition or the oscillator strength, were determined. Electrical conductivity of a-GaN was measured in a different range of temperatures. Then, activation energy of a-GaN thin films was calculated which equalled E _a = 0:434 eV.     

Effects of deposition temperature and hydrogen flow rate on the properties of the Al-doped ZnO thin films and amorphous silicon thin-film solar cells

A compound of 98 mol% ZnO and 1 mol% Al₂O₃ (AZO, Al:Zn = 98:2) was sintered at 1350 °C as a target and the AZO thin films were deposited on glass using a radio frequency magnetron sputtering system. The effects of deposition temperature (from room temperature to ～300 °C) on the optical transmission spectrum of the AZO thin films were studied. The Burstein–Moss shift was observed and used to prove that defects in the AZO thin films decreased with increasing deposition temperature. The variations in the optical band gap (E _g) values of the AZO thin films were evaluated from plots of (αhv)²=c(hν?E _g), revealing that the measured E _g values increased with increasing deposition temperature. The effects of the H₂ flow rate during deposition (0 %～11.76 %, deposition temperature of 200 °C) on the crystallization, morphology, resistivity, carrier concentration, carrier mobility, and optical transmission spectrum of the AZO thin films were measured. The chemical structures of the Ar-deposited and 2 % H₂-flow rate-deposited AZO thin films (both were deposited at 200 °C) were investigated by XPS to clarify the mechanism of improvement in resistivity. The prepared AZO thin films were also used as transparent electrodes to fabricate amorphous silicon thin-film solar cells, and their properties were also measured.