Electrical and optical properties of thin p-type films prepared by vacuum evaporation from the chalcopyrite CuInSe2

The electrical and optical properties of thin films prepared by vacuum evaporation from the chalcopyrite CuInSe₂ are discussed in relation to their structure and deposition parameters. It is shown that p-type films may contain CuSe or Cu_{2 ? x}Se as a second phase and that the presence of Cu_{2 ? x}Se is particularly difficult to identify by X-ray diffraction.     

铝诱导晶化真空蒸镀多晶硅薄膜的研究

采用真空蒸镀的方法在玻璃衬底上沉积1层非晶硅薄膜,再通过铝诱导晶化的方法制备出晶粒分布较均匀、晶粒尺寸0.5～5μm、晶化率达到89%的多晶硅薄膜。研究了衬底距离、衬底温度、退火温度对薄膜表面形貌、晶粒尺寸和分布及晶化率的影响。结果表明适中的衬底距离下得到的薄膜晶粒分布均匀,表面平整度好,薄膜厚度较大。薄膜的晶化率随着衬底温度和退火温度的提高而增大;随着退火温度的进一步提高,薄膜的晶化率达到最大值然后降低。     

Some physical properties of CuInSe2 thin films

Semiconducting thin films of CuInSe₂ have been grown by thermal annealing in air of evaporated layers of Cu, In and Se on glass substrates. The structure of the films has been studied using the X-ray diffraction (XRD). The films were polycrystalline and showed mixture phases (binary and ternary) depending on the annealing temperature. The electrical properties revealed resistivity range of 10¹–10⁴Ωcm, respectively. The resistivity influenced with the annealing temperature and decreased with increasing temperature. The films have been analyzed for optical band gap.     

Effects of water on the growth of aluminium films deposited by vacuum evaporation

Aluminium films 500 nm thick were deposited onto oxidized silicon wafers by electron gun evaporation at 250°C. The evaporation rates were 0.5 and 1.5 nm s^-1. The water partial pressure p_H2O during evaporation was varied between 1.8 × 10^-6 and 1.5 × 10^-3 Pa. It was shown that the water partial pressure has a marked effect on the growth and the morphology of the deposited aluminium films as studied by scanning electron microscopy. At low water partial pressures a faceted surface structure is obtained. With increasing p_H2O the layer becomes rougher until a maximum is reached, after which the layer becomes smooth again and a granular structure is obtained. The changes in the morphology are accompanied by changes in the structural, optical and electrical properties. The observed phenomena can be explained by the dissociative adsorption of water and the formation of oxide-hydroxide phases on the surface of the crystallites. Finally, it was shown that, under the influence of the electron gun, large changes take place in the composition of the residual gas.     

The growth and the interfacial layer of CdZnTe nano-crystalline films by vacuum evaporation

Nano-crystalline CdZnTe films were fabricated by thermal vacuum evaporation. The structure and surface morphology of the CdZnTe films were determined by XRD and SEM. The CdZnTe films were poly-crystalline with preferential (111) orientation. The CdZnTe films exhibited a typical particle size of 15 nm and a blue shift in the absorption with an effective band gap of 2.26 eV. An amorphous Te interfacial layer with thickness of 3 nm was observed with high resolution transmission electron microscopy, which should be formed at the initial stage of the growth. This is because the equilibrium vapor pressure of Cd is largely higher than that of Te₂ at the growth temperature, and the desorption rate of Cd atoms is much higher than that of and Te₂ molecules. The amorphous interfacial layer should be favorable for the formation of nano-crystalline CdZnTe film.     

The growth and the interfacial layer of CdZnTe nano-crystalline films by vacuum evaporation

Nano-crystalline CdZnTe films were fabricated by thermal vacuum evaporation. The structure and surface morphology of the CdZnTe films were determined by XRD and SEM. The CdZnTe films were poly-crystalline with preferential (111) orientation. The CdZnTe films exhibited a typical particle size of 15 nm and a blue shift in the absorption with an effective band gap of 2.26 eV. An amorphous Te interfacial layer with thickness of 3 nm was observed with high resolution transmission electron microscopy, which should be formed at the initial stage of the growth. This is because the equilibrium vapor pressure of Cd is largely higher than that of Te₂ at the growth temperature, and the desorption rate of Cd atoms is much higher than that of and Te₂ molecules. The amorphous interfacial layer should be favorable for the formation of nano-crystalline CdZnTe film.     

真空热蒸发镀CIAS薄膜

采用真空热蒸发方法在普通玻璃基底上制备Cu In0.7Al0.3Se2(CIAS)薄膜,并对之进行450℃真空硒化退火处理。结果表明,制备的CIAS薄膜具有黄铜矿结构并且以(112)晶面优先生长。真空硒化退火后,薄膜晶体结构更完整,晶粒长大,成分分布均匀,更接近CIAS晶体的化学计量比。薄膜为P型半导体,退火后的薄膜禁带宽度减小至1.38 e V,带电粒子数下降至2.41E+17 cm-3,带电粒子迁移率增加至5.29 cm2/(N·s),电阻率升高至4.9Ω·cm。     

大规模真空蒸镀二氧化钛薄膜及其表征

采用大型真空镀膜设备在玻璃基底上蒸镀二氧化钛(TiO2)薄膜,并对TiO2薄膜进行了SEM、AFM、XRD、紫外可见光吸收光谱、亲水性的测试及分析,探讨了退火温度对薄膜性能的影响.结果表明制备的TiO2薄膜具有良好的均匀性.在室温条件下,TiO2薄膜具有无定型的结构;在300～500℃的条件下,TiO2薄膜退火2h后以锐铁矿晶型为主,600℃退火的TiO2薄膜明显向金红石型转变.随退火温度的升高,薄膜对紫外光和可见光的吸收有明显提高,并出现了明显的红移现象.另外,亲水性也随退火温度的升高而变强,500和600℃退火的TiO2薄膜表面出现超亲水性.     

真空蒸发制备Sb掺杂CdTe薄膜

采用真空蒸发技术在玻璃衬底上制备了Sb掺杂的CdTe薄膜,薄膜为沿(111)晶向择优生长的立方闪锌矿结构的CdTe,结果表明Sb掺杂使得薄膜表面更加均匀致密,改善了薄膜的结晶状况,增大了薄膜的光吸收范围,同时也使薄膜的带隙宽度有所减小,大大降低了薄膜的电阻率.     

Studies on polycrystalline Cd0.96Zn0.04Te thin films prepared by vacuum evaporation

Polycrystalline Cd_0.96Zn_0.04Te thin films are deposited onto glass substrates (Corning 7059) kept at room temperature by vacuum evaporation. The films exhibit zinc blende structure with predominant (1 1 1) orientation. The rms roughness of the films evaluated by atomic force microscope is 3.7 nm. The band gap energy of the films measured by optical transmittance measurement is 1.539 eV. The photoluminescence (PL) spectrum of the films shows intense emission due to free and bound exciton recombination and no emission associated with crystal imperfection and PL line shapes give indications of the high quality of the layers. These films have been implanted with properly mass analyzed Boron ions (¹⁰B⁺) and the effect of implantation has been analyzed by X-ray diffraction, Raman scattering and optical transmittance measurements and the results are explained on the basis of the implantation induced surface roughness and lattice disorder.     

Abrasive wear of thick silica films prepared by vacuum evaporation

We investigate the wear behaviour of thick silica films 2–3m thick evaporated on a polymethylmethacrylate substrate in vacuum. The wear test is performed with kaolin mineral powder suspended in water. Abrasive wear is not affected by silica film hardness varying from 100 to 550 kg mm^–2, which corresponds to film preparation pressures ranging from 5×10^–3 to 5×10^–5 torr. The wear characteristics and the appearance of the wear tracks are strong evidence that abrasive wear of the deposited silica films consists of the mechanical and molecular removal of a hydrolysed silica film surface by abrasive kaolin grains. This is very similar to the case of glass polishing.     

Structural and optical characterization of CuInS2 thin films grown by vacuum evaporation method

Structural and optical properties of CuInS₂ thin films grown by the single-source thermal evaporation method have been studied. The films were annealed from 100 to 500 °C after an evaporation in air. The surface morphology was investigated by scanning electron microscopy. The maximum grain size of the samples after annealing at 400 °C was over 500 nm. The EPM analysis concluded that the polycrystalline CuInS₂ thin films after annealing below 100 °C were Cu-rich, and those annealed above 200 °C were In-rich. The bandgap energy of the CuInS₂ films after annealing above 300 °C was about 1.48 eV.     

Flash-evaporated thin films of CuInSe2

Flash-evaporated technique has been developed for deposition of CuInSe₂ thin films. A control over the stoichiometry and chemical composition of the films has been obtained by varying the deposition parameters. Single phase chalcopyrite structure films with optical gap ∼ 1·15 eV have been obtained. The electronic properties of the films have been tailored for solar cell applications.     

Plasma-enhanced vacuum evaporation of perpendicular Co-Cr magneticthin films

A novel plasma-enhanced vacuum evaporation process is described for the fabrication of perpendicular Co-Cr thin films for high-density magnetic tape recording. The plasma is excited by an RF coil placed between the source and substrate and is supported by the metal evaporant itself without the need for a carrier gas. The primary effect of the plasma is to increase the perpendicular coercivity, thus allowing a reduction in substrate temperature for better compatibility with low-temperature (and cheaper) polymer supports. It is found that Cr concentration, substrate temperature, and substrate surface preparation are critical to the development and control of perpendicular magnetic characteristics. Transmission electron microscopy (TEM) cross-section analysis reveals a slight increase in grain diameter from film bottom to top, even for films with well-oriented initial layers. A survival-of-the-tallest grain growth model in the high-mobility limit is proposed to explain some of the observed features