C+注入a-SiNx：H薄膜的微结构及光发射的研究

常温下对低压化学气相沉积制备的纳米硅镶嵌结构的a-SiN_x:H薄膜进行低能量高剂量的C⁺注入后,在800~1200℃高温进行常规退火处理。X射线光电子能谱(XPS)及X射线光电子衍射(XRD)等实验结果表明,当退火温度由800℃升高到1200℃后,薄膜部分结构由SiC_xN_y转变成SiN_x和SiC的混合结构。低温下利用真空紫外光激发,获得分别来自于SiN_x、SiC_xN_y、SiC的,位于2.95,2.58,2.29 eV的光致发光光谱。随着退火温度的升高,薄膜的结构发生了变化,发光光谱也有相应的改变。

Photoluminescence of SiCN Thin Films Prepared by C+ Implantation into Amorphous SiNx:H

Generally,silicon carbon nitride(SiCN) thin films have attracted much interest for a wide rang of applications due to their excellent thermal properties,large bonding energy and adjustable band gaps varying from UV to visible light range.Hydrogenated amorphous silicon nitride films(a-SiN_x:H) were implanted by C⁺ ions with 30 keV and the doping dose of 2×10¹⁷ ions cm^-2 at room temperature and then treated by annealing for 2 hours at 800,1000 and 1200℃,respectively.The composition and bonding structure of SiCN were analyzed by X-ray photoelectron spectroscopy(XPS),Raman spectroscopy and X-ray diffraction(XRD).The luminescent properties of SiCN have been studied by synchrotron radiation at RT and 20 K,respectively.XPS results showed that the C-Si,C=N and Si-N bonds existed in the films.When the films were annealed at 800℃ for 2 hours,two structures could be found at different depths.SiC and SiN_x were found in the depth range of 50~100 nm,while the SiC_xN_y still existed at the depth of 250 nm.And the Raman spectrum of the SiCN film shows two peaks at approximately 1350 and 1600 cm^-1,which corresponded to D and G bands of sp²-carbon.The presence of this pronounced Raman band indicates SiC_xN_y structure within the film.Furthermore,XRD indicated that the SiCN films annealed at 1200℃ consisted of the structures of α-Si₃N₄,β-Si₃N₄ and β-SiC.After SiCN was annealed at 800℃,four luminescent emission bands of SiCN under the excitation of 197 nm at 20 K were observed,which were located at 2.95,2.58,2.29 and 2.12 eV and were attributed to the emissions of SiN_x,SiC_xN_y,SiC and SiO_x respectively.However,after the film was annealed at 1200℃,for the modification of particle state and the improvement of film structures,the inten-sity of luminescence signals at 2.58 and 2.29 eV were different.The PL signature in SiCN films can be used to monitor the physical structure,and to point out their defect content.