摘要
在室温下利用等离子体增强化学气相淀积(PECVD)方法制备出非晶掺氧氮化硅(a-SiN_x∶O)薄膜.通过改变硅烷(SiH_4)和氨气(NH_3)流量比R,可实现薄膜光致发光(PL)峰位在2.06~2.79eV可见光能量范围内的波长调制.光吸收谱中光吸收峰位与PL峰位重叠,表明薄膜发光来源于光吸收边以下0.65eV左右处的缺陷态.通过对傅里叶变换红外光谱(FTIR)的键浓度分析和X射线光电子能谱(XPS)Si 2p峰的分峰拟合,发现薄膜PL强度的增强与N-Si-O键合浓度的升高紧密相关.R=1∶4时,PL强度与N-Si-O键合浓度同时达到最大.进一步证明了a-SiN_x∶O薄膜中的发光缺陷态与N-Si-O键合结构密切相关.此外,PL峰位随流量比R的增大而发生红移的现象可能源自于N-Si-O组态转变造成的缺陷态密度最大位置处的能级偏移和光学带隙变窄引起的价带顶上移.
In order to investigate deeply the luminescent mechanism of amorphous oxygenated Silicon nitride（a-SiNx O） film,the a-SiNx ：0 thin films were prepared by plasma enhanced chemical vapor deposition （PECVD）at room temperature. By adjusting the flow rate ratio （R） of silane （Sill4） to ammonia （NH3）, photoluminescence （PL） with peak position tunable in the visible range from 2.06 to 2.79 eV can be realized. In absorption spectra of a-SiNx： O films ,the location of absorption peaks were in good agreement with those of corresponding PL. It suggested that the PL originates from radiative recomhination at luminescent defect state. Based on the calculation of the energy distance between optical absorption edge and the position of absorption peak, the location of this luminescent defect state was determined to be about 0. 65 eV underneath the absorption edge. From the analysis on bonding concentration in Fourier transform infrared（FTIR）spectra and the deconvolution of Si 2p peak in X-ray photoelectron spectra（XPS） ,it was found that the enhancement of PL was proportional to the increase of N-Si-O bonding concen- tration. Both of the PL intensity and N-Si-O bonding concentration reached the maximum when R = 1 ： 4. The experimental results further certified that luminescent defect state in a-SiNx： O film was closely related to N-Si-O bonding configuration. Finally, an energy band model for photoluminescence of a-SiNx ： O films was constructed. The carriers were pumped to the exited states,and then relaxed to energy levels of defect states, afterwards recombined via transition between defect state levels and valence band maximum to emit photons. In addition, the phenomenon of the redshift of PL peak with the increase of the flow rate ratio R may arise from two possible reasons, i. e. the shifting of energy level at the maximum position of density of defect state caused by the transformation of N-Si-O bonding configuration and upward shift of valence band maximum arising from the reduction of optical band gap.
出处
《南京大学学报（自然科学版）》
CAS
CSCD
北大核心
2017年第3期392-398,共7页
Journal of Nanjing University（Natural Science）
基金
江苏省高校自然科学研究面上项目(14KJB510014)
南京大学固体微结构物理国家重点实验室开放课题基金(M29026)
江苏省"青蓝工程"
