Publications (3)1.08 Total impact
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Article: Adjustment of the selenium amount during ion beam sputtering deposition of CIS thin films
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ABSTRACT: CuInSe2 (CIS) films were prepared by ion beam sputtering depositing Cu, In and Se layers sequentially on BK7 glass substrates and annealing the 3-layer film in the same vacuum chamber. The adjustment of the Se amount in the film was achieved by controlling the sputtering time of the Se target. X-ray diffraction pattern shows CIS films have chalcopyrite structure and preferential (112) orientation when the sputtering of the Se layer is between 60 and 180min. It also can be seen that the most intense and narrow peak indicates the highest crystallinity for the sample with sputtering Se of 60min, which is in agreement with the Raman measurement. The content of Cu, In and Se in the film deviates from 1, 1 and 2 with increasing the sputtering time of the Se target. Direct band gap energy between 0.96 and 1.05eV, depending on the Se amount, and a high absorption coefficient of 105cm−1 are found. The measured film resistivities vary from 0.01 to 0.05Ωcm. Thus, the structural, optical and electrical characteristics of the CIS thin films were dependent on the Se amount during the fabrication of films and after fitting the sputtering time of Se, an optimization of the properties and a saving of Se consumption were achieved.Journal of Materials Science Materials in Electronics 05/2012; 21(9):897-901. · 1.08 Impact Factor -
Article: Composition-Dependent Characterization of Sb2Te3 Thin Films Prepared by Ion Beam Sputtering Deposition
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ABSTRACT: The optimization of ion beam sputtering deposition process for Sb2Te3 thin films deposited on BK7 glass sub-strates is reported. The influence of composition ratio on the thermoelectric properties is investigated. X-ray diffraction shows that the major diffraction peaks of the films match with those of Sb2Te3. Hall effect and See-beck coefficient measurement reveal that all the samples are of p-type. The Sb2Te3 thin films exhibit the Seebeck coefficient of 190 íµí¼Vk −1 and the electrical conductivity of 1.1 × 10 3 Scm −1 when the atomic ratio of Sb to Te is 0.65. Carrier concentration and motility of the films increase with the increasing atomic ratio of Sb to Te. The Sb2Te3 film with a maximum power factor of 2.26 × 10 −3 Wm −1 K −2 is achieved when annealed at 400 ∘ C. Raman measurement shows that the main peaks are at about 120 cm −1 , 252 cm −1 and 450 cm −1 , in agreement with those of V-VI compound semiconductors. Alloys based on V-VI compound semiconductors, with A 2 B 3 -type, have been extensively studied be-cause of their excellent thermoelectric properties and potential applications in efficient thermoelectric de-vices such as thermoelectric generators, coolers and optical storage systems. [1,2] The research results indi-cate that thin films and nanowires would have a higher figure of merit (ZT) [3] due to their stronger quantum confinement. [4] Therefore, various techniques, includ-ing flash evaporation, [5] sputtering, [6] electrochemi-cal deposition [7−9] and chemical-vapor deposition [10] have been used to grow thermoelectric thin films and nanowires. Antimony telluride (Sb 2 Te 3) is an important V-VI thermoelectric material at room temperature due to its narrow-band gap and lager figure of merit (ZT) value. [11−13] Compared with bulk Sb 2 Te 3 ma-terials, the ZT value of Sb 2 Te 3 thin films has been enhanced greatly. However, only a few studies have been conducted on fabricating Sb 2 Te 3 thin films and nonawires. [12−14] The most difficult task for preparing Sb 2 Te 3 thin films is controlling the composition of the thin films. Because the vapor pressure of Te is so high and re-evaporation of Te prevents the formation of Sb 2 Te 3 . Actually, ion beam sputtering deposition is a very attractive technique since it combines a high de-position rate with a great versatility in the deposition of films by adjusting the target composition and con-trolling the sputtering energy. In addition, preparing Sb 2 Te 3 thin films by ion beam sputtering deposition (IBSD) is rarely reported. In this work, high quality Sb 2 Te 3 thin films are prepared by IBSD. The struc-tural and electrical properties of the films are investi-gated. Sb 2 Te 3 thin films were deposited on BK7 glass substrates by IBSD in argon ambience. The tar-get was made of fan-shaped high purity Sb (99.99%) and Te(99.99%) plates. The Sb/Te proportion was controlled by adjusting the ratio of the correspond-ing plate areas. The background pressure was 7.0 × 10 −4 Pa and the work pressure was 6.1×10 −2 Pa. The substrates were ultrasonically cleaned in acetone and alcohol for 10 min, respectively. Prior to Sb/Te de-position, a 15-min sputter cleaning process was per-formed to remove the native oxides and contami-nants on the target surfaces. Four samples (named as S1 ∼ S4) with different Sb/Te compositions were prepared at room temperature. The deposition time was 60 min. The sample with the best power factor (PF = íµí»¼ 2 íµí¼) was annealed at 400 ∘ C for one hour in the vacuum chamber (named as S5). More details on sample preparation are given in Table 1 where íµí± ato is the atomic ratio of Sb to Te.01/2010; 27(73). -
Article: The influence of film thickness on the transparency and conductivity of al-doped ZnO thin films fabricated by ion-beam sputtering
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ABSTRACT: To evaluate the influence of film thickness on the structural, electrical, and optical properties of Al-doped ZnO (AZO) films, a set of polycrystalline AZO samples with different thickness were deposited on glass substrates by ion-beam sputtering deposition (IBSD). X-ray diffraction (XRD), atomic force microscopy (AFM), energy-dispersive x-ray spectroscopy (EDS), four-point probe measurements, and spectrophotometry were used to characterize the films. XRD showed that all the AZO films had preferred c-axis orientation. The ZnO (110) peak appeared, and the intensity increased, with increasing thickness. All the samples exhibited compressive intrinsic stresses. AFM showed that the grain size along with the root-mean-square (RMS) roughness increased with increasing thickness. The decrease of resistivity is due to the corresponding change in grain size, surface morphology, and chemical com-position. The average optical transmittance of the AZO films was over 80%, and a sharp fundamental absorption edge with red-shifting was observed in the visible region. The optical band gap decreased from 3.95 eV to 3.80 eV when the AZO film thickness increased from 100 nm to 500 nm.
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2010
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Shenzhen University
Shenzhen, Guangdong Sheng, China
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