Sol-Gel法制备ZnO:Cd薄膜及结构特性研究

Preparation of Cd-doped ZnO Thin Films by Sol-Gel Technique and Investigation on Structural Properties

采用Sol—Gel法，结合旋转涂覆技术在Si（100）衬底上制备了ZnO：Cd薄膜，并对其在600～800℃热处理。X-射线衍射仪（XRD）结果表明，ZnO：Cd薄膜具有与ZnO同样的六角纤锌矿结构，且随着热处理温度的升高，（002）衍射峰的强度逐渐增强。峰半高宽（FWHM，ZnO（002））不断减小，并沿c轴择优取向生长；Cd掺杂后，未出现CdO或其他镉化物等杂质相，但在（002）峰-峰顶出现了分叉（多峰）现象。随着退火温度的升高，多峰消失，但这方面的报道甚少。扫描式电子显微镜（SEM）显示ZnO：Cd晶粒粒径分布情况及表面形貌特征。以石英为基片的透射光谱实验计算表明，ZnO：Cd薄膜的禁带宽度平均为3．10eV；800℃，x（Cd）=8％样品的禁带宽度为2．80eV，比纯ZnO晶体禁带宽度（3．30eV）明显减小，这说明适度掺镉可降低薄膜的光学禁带宽度。

ZnO ：Cd films were prepared on Si（100） substrates by the Sol-Gel process using a spinning-technical. The Cd-doped ZnO films showed a hexagonal wurtzite structure and c-axis orientation as observed by XRD. With the increase of heat-treating temperature, the intensity of diffraction peak increased and FWHM reduced. When doping Cd, CdO related peaks were not found, but many peals were found in the （002） peal. With the increase of annealing temperature, it was few reported that many peals disappeared. The SEM images of ZnO ：Cd showed its spherical and character of phase formation. Optical transmittance spectra of ZnO： Cd films on quartz substrates indicated that bandgap of the films were 3.10 eV on average. The bandgap of the film at 8%Cd under 800 ℃ annealing temperature was 2.80 eV. The bandgap was apperanty narrower than that of ZnO bulk crystal（3.30 eV）. It was practicable to reduce optical bandgap of the thin films by temperate Cd-doped method.