光谱学与光谱分析, 2017, 37 (5): 1357, 网络出版: 2017-06-20  

Y掺杂Si纳米线的光致发光特性

Photoluminescence Properties of Y Doped Si Nanowires
作者单位
1 河北大学电子信息工程学院, 河北 保定 071000
2 清华大学微电子学院, 北京 100084
3 河北大学河北省数字医疗工程重点实验室, 河北 保定 071000
摘要
以n型单晶Si(111)为衬底, 利用Au作为催化剂, 在温度、 N2流量和生长时间分别为1 100 ℃, 1.5 L·min-1和60 min的条件下, 基于固-液-固生长机制, 生长了直径为60~80 nm、 长度为数十微米的高密度Si纳米线。 随后, 以Y2O3粉末为掺杂源, 采用高温扩散方法对Si纳米线进行了钇(Y)掺杂。 利用扫描电子显微镜、 X射线衍射仪和荧光分光光度计对不同掺杂温度(900~1 200 ℃)、 掺杂时间(15~60 min)和N2流量(0~400 sccm)等工艺条件下制备的Y掺杂Si纳米线的形貌、 成分、 结晶取向以及激发光谱和发射光谱特性进行了详细的测量和表征。 结果表明, 在掺杂温度为1 100 ℃, N2流量为200 sccm、 掺杂时间为30 min和激发波长为214 nm时, Y掺杂Si纳米线样品表现出较好的发光特性。 样品分别在470~500和560~600 nm范围内出现了两条发光谱带。 560~600 nm的发光带由两个发光峰组成, 峰位分别为573.6和583.8 nm, 通过结构分析可以推测, 这两个发光峰是由Y3+在Si纳米线的带隙中引入的杂质能级引起的。 而470~500 nm较宽的发光带同样来源于Y离子在Si纳米线带隙中引入的与非晶SiOx壳层中氧空位能级十分接近的杂质能级。
Abstract
High- density silicon nanowires were grown on the n-(111) single crystal silicon wafer based on solid-liquid-solid mechanism using Au films as catalyst. Then silicon nanowires were doped with yttrium (Y) with high temperature diffusion method using Y2O3 powder as doping source. The experimental parameters were doping temperature of 900~1 100 ℃, doping time of 15~60 min and N2 flow rate of 0~400 sccm. The morphology of nanowires was measured with scan electron microscopy (SEM). The composition and crystalline orientation of nanowires were analyzed with X-ray diffraction (XRD). The measurement and characterization of excitation and emission spectrum of silicon nanowires were carried out with F-4600 fluorescence spectrophotometer. The SEM images show that the curved, winding silicon nanowires with uniformly size and high density were grown on the surface of silicon wafer. The average diameter and length of silicon nanowires are about 100 nm and several tens of microns, respectively. The photoluminescence spectra of undoped silicon nanowires were measured with an excitation wavelength of 214 nm at room temperature, which exhibits a broad blue emission in the range of 450~480 nm with the center peak of 470 nm. The blue emission band is derived from the oxygen vacancies in the amorphous SiOx shell of the Si nanowires. Also, the photoluminescence spectra of Y doped silicon nanowires were measured, which consists of a broad blue emission band in the range of 470~500 nm with the center peak located near the 488 nm and a narrow yellow-green luminescence band in the range of 560~600 nm with two emission peaks of 573.6 and 583.8 nm. The experimental results show that with the increase of doping temperature from 900 to 1 200 ℃, the strength of the yellow-green light emission band has experienced increase firstly and then decrease, the maximum value appears at 1 100 ℃. In addition to the temperature, a similar phenomenon was also observed by changing the doping time and nitrogen flow. The yellow-green luminescence intensity of Y doped silicon nanowires increases firstly and then decreases with the increasing of the doping time (from 15 to 60 min) and nitrogen flow rate (from 0 to 400 sccm), the maximum value appears at 30 min and 200 sccm, respectively. In order to explore the source of yellow-green emission band in the range of 560~600 nm of Y doped silicon nanowires, X-ray diffraction is carried out. The results show that two major compounds can be formed, namely, Y2Si2O7 and Y2SiO5 with high temperature diffusion Y into the silicon nanowires. We believe that Y3+ can introduce impurity energy levels in the band gap of silicon nanowires. Therefore, the luminescence mechanism can be described as follows: First, the silicon nanowires absorb photons, forming photo electrons in the conduction band. Then, electrons relax to the impurity levels. Finally, electrons jump to the valence band of silicon nanowires, and emitting yellow-green light.

张津豪, 刘绰, 李婉, 郝肖, 吴一, 范志东, 刘磊, 马蕾. Y掺杂Si纳米线的光致发光特性[J]. 光谱学与光谱分析, 2017, 37(5): 1357. ZHANG Jin-hao, LIU Chuo, LI Wan, HAO Xiao, WU Yi, FAN Zhi-dong, LIU Lei, MA Lei. Photoluminescence Properties of Y Doped Si Nanowires[J]. Spectroscopy and Spectral Analysis, 2017, 37(5): 1357.

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