氧、氮掺杂非晶硅基薄膜的荧光

Photoluminescence from O, N Doped Amorphous Si∶H Thin Film

采用PECVD方法分别沉积了SiOx∶H和SiOxNy∶H薄膜 ,测量了其荧光特性。在SiOx∶H薄膜中观察到 3 0 0～ 570nm强荧光辐射带 ,并发现其中心位置随着氧含量的增加而红移的现象。在合适的氧含量条件下 ,荧光带主峰位于蓝光波段 ,并具有分立峰结构。在SiOxNy∶H薄膜中 ,荧光谱由 2 50～ 4 0 0nm、50 0～ 70 0nm两个荧光带和 3 70nm、73 0nm两组分立荧光峰组成。分立峰强度随薄膜中的氮含量增加而升高 ;荧光带中心位置受到沉积过程中氢的流量调制 ,当氢流量增加时 ,发射带的中心位置产生蓝移。

The discovery of room temperature photoluminescence from silicon based materials has stimulated the renewed interest in the field of silicon based optoelectronics. In the past few years, much effort has been directed in searching for better silicon based light emitting materials. Through doping oxygen in silicon , considerable light emission in the variant range has been successfully achieved. But very few studies have been carried out on the photoluminescence property of silicon material codoped by oxygen and nitrogen. In the paper, several strong luminescence bands and peaks from oxygen and nitrogen codoped silicon thin film were reported. The thin films were deposited onto silicon wafers by plasma enhanced chemical vapor deposition (PECVD) using SiH 4, H 2, O 2 and NH 3 at 300℃ with thickness about 500nm. Changing the flow rate of discharge gases during deposition modulated the thin film composition. The depositing chamber was evacuated to 10 -4 Pa, depositing pressure was 80Pa, and discharge r f. power density was 0 15W/cm 2. The photoluminescence spectra of thin films were measured using RF 5301 photoluminescence spectrometer at room temperature. The results of X ray diffraction measurement show that the structure of thin films is amorphous. The thin film composition varies with changing the flow rate of discharge gases during deposition, and assumes different photoluminescence properties. In the SiO x ∶H thin film, strong photoluminescence at about 300～570nm was observed at room temperature. The central position shifts towards lower energy with the increase of oxygen content. When the partial pressure of O 2 during deposition is increased to 15Pa, blue light band containing distinguishable photoluminescence peaks is achieved. Photoluminescence spectrum of SiO x N y ∶H thin film is composed of bands and distinguishable peaks. The photoluminescence bands are localized at 250～400nm and 500～700nm, and central position depends on the flow rate of H 2 during deposition. When the flow rate of H 2 increases, central position shifts towards higher energy. The distinguishable photoluminescence peaks centered at about 370nm and 730nm. They strengthen with the increase of N content in the thin film. Above experimental results show that photoluminescence from thin film is related to O and N impurities . It is suggested that photoluminescence possibly originates from light emitting centers related to O and N impurity levels.