Manikandan E, Moodley M K, Sinha Ray S, Panigrahi B K, Krishnan R, Padhy N, Nair K G M, Tyagi A K
DST/CSIR Nanotechnology Innovation Centre, National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria 0001, Republic of South Africa.
J Nanosci Nanotechnol. 2010 Sep;10(9):5602-11. doi: 10.1166/jnn.2010.2478.
Zinc Oxide (ZnO) is a promising candidate material for optical and electronic devices due to its direct wide band gap (3.37 eV) and high exciton binding energy (60 meV). For applications in various fields such as light emitting diode (LED) and laser diodes, growth of p-type ZnO is a prerequisite. ZnO is an intrinsically n-type semiconductor. In this paper we report on the synthesis of Zinc Oxide-Carbon (ZnO:C) thin films using pulsed laser deposition technique (PLD). The deposition parameters were optimized to obtain high quality epitaxial ZnO films over a carbon layer. The structural and optical properties were studied by glazing index X-ray diffraction (GIXRD), photoluminescence (PL), optical absorption (OA), and Raman spectroscopy. Rutherford backscattering spectroscopy (RBS), scanning electron microscopy with energy dispersive spectroscopy (SEMEDS) and atomic force microscopy (AFM) were employed to determine the composition and surface morphology of these thin films. The GIXRD pattern of the synthesized films exhibited hexagonal wurtzite crystal structure with a preferred (002) orientation. PL spectroscopy results showed that the emission intensity was maximum at -380 nm at a deposition temperature of 573 K. In the Raman spectra, the E2 phonon frequency around at 438 cm(-1) is a characteristic peak of the wurtzite lattice and could be seen in all samples. Furthermore, the optical direct band gap of ZnO films was found to be in the visible region. The growth of the epitaxial layer is discussed in the light of carbon atoms from the buffer layer. Our work demonstrates that the carbon is a novel dopant in the group of doped ZnO semiconductor materials. The introduction of carbon impurities enhanced the visible emission of red-green luminescence. It is concluded that the carbon impurities promote the zinc related native defect in ZnO.
氧化锌（ZnO）因其直接宽带隙（3.37电子伏特）和高激子束缚能（60毫电子伏特），是光学和电子器件中一种很有前景的候选材料。对于发光二极管（LED）和激光二极管等各种领域的应用而言，p型ZnO的生长是一个先决条件。ZnO是一种本征n型半导体。在本文中，我们报道了使用脉冲激光沉积技术（PLD）合成氧化锌 - 碳（ZnO:C）薄膜。优化了沉积参数，以在碳层上获得高质量的外延ZnO薄膜。通过掠入射X射线衍射（GIXRD）、光致发光（PL）、光吸收（OA）和拉曼光谱研究了其结构和光学性质。采用卢瑟福背散射光谱（RBS）、带能谱的扫描电子显微镜（SEMEDS）和原子力显微镜（AFM）来确定这些薄膜的成分和表面形貌。合成薄膜的GIXRD图谱显示出具有择优（002）取向的六方纤锌矿晶体结构。PL光谱结果表明，在573 K的沉积温度下，发射强度在 -380 nm处最大。在拉曼光谱中，约438 cm⁻¹处的E2声子频率是纤锌矿晶格的特征峰，在所有样品中都能看到。此外，发现ZnO薄膜的光学直接带隙在可见光区域。根据来自缓冲层的碳原子讨论了外延层的生长。我们的工作表明，碳是掺杂ZnO半导体材料中的一种新型掺杂剂。碳杂质的引入增强了红绿发光的可见发射。得出的结论是，碳杂质促进了ZnO中与锌相关的本征缺陷。
