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采用等离子体增强化学气相沉积法,以NH3与SiH4为反应气体,n型单晶硅为衬底,低温(220°C)沉积了富硅氮化硅(SiNx)薄膜.在N2氛围中,于500—1100C范围内对样品进行了热退火处理.采用Raman光谱技术分析了薄膜内硅量子点的结晶情况,结果表明,当退火温度低于950°C时,样品的晶化率低于18%,而当退火温度升为1100°C,晶化率增加至53%,说明大部分硅量子点都由非晶态转变为晶态.实验通过Fourier变换红外吸收(FTIR)光谱检测了样品中各键的键合结构演变,发现Si—N键和Si—H键随退火温度升高向高波数方向移动,说明了薄膜内近化学计量比的氮化硅逐渐形成.实验还通过光致发光(PL)光谱分析了各样品的发光特性,发现各样品中均有5个发光峰,讨论了它们的发光来源,结合Raman光谱与FTIR光谱表明波长位于500—560nm的绿光来源于硅量子点,其他峰则来源于薄膜内的缺陷态.研究了硅量子点的分布和尺寸对发光带移动的影响,并根据PL峰位计算了硅量子点的尺寸,其大小为1.6—3nm,具有良好的限域效应.这些结果有助于制备尺寸不同的硅量子点和基于硅量子点光电器件的实现
A silicon-rich silicon nitride (SiNx) thin film was deposited at low temperature (220 ° C) using a plasma-enhanced chemical vapor deposition method with NH3 and SiH4 as reactant gases and n-type single crystal silicon as a substrate. The samples were annealed in the temperature range of 500-1100 C. The Raman spectroscopy was used to analyze the crystallization of silicon quantum dots in the film.The results show that the crystallization rate of the samples is less than 18% when the annealing temperature is lower than 950 ° C, , While the crystallization rate increased to 53% when the annealing temperature was increased to 1100 ° C, indicating that most of the silicon quantum dots are transformed from amorphous to crystalline state.The Fourier transform infrared absorption spectroscopy (FTIR) The results show that the Si-N bond and Si-H bond move in the direction of higher wavenumber with the increase of annealing temperature, which indicates that the near-stoichiometric SiN in the film is gradually formed.The experiment is also carried out by photoluminescence PL). The results show that there are five luminescence peaks in each sample. The luminescence sources of each sample are discussed. The combination of Raman spectroscopy and FTIR spectroscopy shows that the green light with the wavelength of 500-560nm comes from silicon quantum dots, The other peaks are derived from the defect state in the thin film Distribution and size of the photoluminescence band, and the size of the silicon quantum dots is calculated according to the PL peak, and the size of the silicon quantum dots is 1.6-3nm with good confinement effect. These results contribute to the preparation of silicon quantum dots with different sizes and Realization of silicon quantum dot photoelectric device