腐蚀法制备SiC量子点粒径调控及尺寸对其光学性能的影响

Particle Size Regulation of SiC Quantum Dots Prepared by Corrosion Method and Effect of Size on Optical Properties

以氢氟酸、硝酸及分析纯硫酸组成的混合液为腐蚀剂,通过化学腐蚀法制备碳化硅量子点。对腐蚀混合液进行超声空化破碎,而后将其置于浓度梯度溶剂中进行高速离心层析裁剪,获得光学性能优异且粒径尺寸可控的碳化硅量子点。本文研究了腐蚀进程中碳化硅量子点微观形貌的演变过程,对SiC量子点的微观结构及发射光谱进行检测分析后,以发射光谱为纽带,建立量子点尺寸、光谱、颜色的关联机制。结果表明,超重力系数设定a=1000、离心时间120 min条件下,距液面位移0、30、60 mm处量子点平均直径约为2、5、7 nm,单一波长激发下随着碳化硅量子点直径由2→5→7 nm的变化,其光致发光相对强度峰值出现由417→435→445 nm的红移,而且发光颜色也相应呈现蓝绿色→绿色→黄绿色的变化规律;进一步研究发现,三种尺寸量子点发射光谱的半峰全宽随取液深度的增加而呈现81→97→106 nm增加的现象,初步分析这是由高速离心层析裁剪后靠近上层液面量子点粒径分布均匀性高于远离上层液面所致。

Silicon carbide quantum dots(QDs)were prepared by simple chemical etching method using a mixture of hydrofluoric acid,nitric acid,and analytically pure sulfuric acid as etchants.Ultrasonic cavitation fragmentation was performed on the corrosive mixture,and then it was subjected to high-speed tomographic cutting in a concentration gradient solvent to obtain silicon carbide QDs with excellent optical properties and controllable particle size.The evolution process of microstructure of SiC QDs during corrosion process,the microstructure and emission spectra of SiC QDs were detected and analyzed,and then correlation mechanism at quantum dots size,spectrum,and color was established by emission spectra as a link.The results show that under the conditions of a=1000 hypergravity coefficient and a centrifugation time of 120 min,the average diameter of QDs at 0,30,and 60 mm displacement from the liquid surface is about 2,5,and 7 nm.Under single wavelength excitation,as the diameter of SiC QDs changes from 2→5→7 nm,the relative intensity peak of photoluminescence shows a red shift from 417→435→445 nm,and the luminescence color also show a corresponding change pattern of blue green→green→yellow green;further research had found that the full width at half maximum of the emission spectra of QDs of three sizes show an increase of 81→97→106 nm with increasing liquid depth.Preliminary analysis suggests that it was due to the higher uniformity of particle size distribution of quantum dots near the upper liquid surface compared to those far away from the upper liquid surface after high-speed centrifugal chromatography cutting.