用射频溅射技术在硅衬底上制备In掺杂ZnO薄膜

Preparation of In-doped ZnO Films on Si Substrates Using Radio Frequency (rf) Reactive Co-sputtering Technique

以金属锌(Zn)和金属铟(In)为靶材采用射频反应共溅射技术在硅(100)衬底上沉积了In掺杂ZnO薄膜。用X射线衍射仪、扫描电子显微镜(SEM)、热探针、四探针和荧光分光光度计分别对样品的结构、表面形貌、导电类型、电阻率和发光特性进行了分析表征。测试结果表明,实验中制备出的ZnO薄膜具有高度的c轴择优取向和小压应力(0.74GPa),薄膜表面平整。样品为n型导电,电阻率为1.6Ω·cm。在室温光致发光谱测量中,首次观察到位于415～433nm的强的蓝紫光双峰发射,发光双峰的半峰全宽约为400meV。讨论了In掺杂对薄膜发光特性的影响。

Over the past few years, wide and direct band gap semiconductors have been intensively studied for their application as blue and ultraviolet light emitters. As a wide gap semiconductor, ZnO has a wide band gap (3.37 eV) and a large binding energy (60 meV). Therefore, ZnO is considered as one of the most promising candidates for short wavelength optoelectronics devices, and it is very important to conduct further studies of the properties of ZnO thin films.In this paper, indium-doped zinc oxides was prepared by radio frequency (rf) reactive co-sputtering on silicon (100) substrate at 430 ℃. Sputtering target were consist of metal zinc (99.99%) and metal indium (99%). Indium content is about 3% (the ratio of indium slices area to that of whole target) on the target. The sputtering gas is a mixture gas of argon (99.97%) and oxygen (99.95%), the partial pressure ratio of oxygen is 0.4. The structure, surfaces morphology, type of conductivity, electrical resistivity and PL spectra of the sample were characterized by X-ray diffractometer, scanning electron microscopy, hot probe, four-point probe and fluorescent spectrophotometer, respectively. There are four main ZnO diffraction peaks in the glancing angle X-ray diffraction patterns, and no diffraction peaks of In_2O_3 or Zn_2In_2O_5 are observed. Therefore, we think that polycrystalline ZnO thin films was prepared by RF reactive co-sputtering . The θ-2θ scan mode X-ray diffraction patterns indicated that the film has highly c-axis orientation and low biaxial compressive stress (0.74 GPa). The 2θ angles of (002) diffraction peak is 34.48° and the full width at half maximum is 0.376°. The surface of the sample was smooth and flat. Compared with un-doped ZnO thin films, low resistivity (1.6 Ω·cm) n-type ZnO thin film was deposited on silicon (100) by doped indium. The blue-violet photoluminescence bi-peak located at 415 nm and at 433 nm is observed when exited with 340 nm wavelength in the photoluminescence (PL) spectrum at room temperature. In this paper, we think that the peak at 415 nm comes from In impurity defects and the peak at 433 nm originates from Zn interstitial defects.