GROWTH AND MICROSTRUCTURES OF ULTRATHIN Bi2Te3 NANOPLATES BY MODIFIED HOT WALL EPITAXY

Ultrathin Bi2Te3 nanoplates have been grown on an oxidized silicon substrate by a modified hot wall epitaxy (HWE) method, in which a quartz plate with holes was employed. The microstructures and optical properties of Bi2Te3 nanoplates were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM) and micro-Raman spectroscopy. The results show that ultrathin Bi2Te3 nanoplates with the thickness of about six quintuple layers (QLs) are obtained, which is difficult for the traditional HWE technique. The Raman vibration mode A(1g)(1) from the nanoplates exhibits an obviously red shift with decreasing thickness. The thickness variation of one nanoplate was obtained by the Raman map derived from the vibration frequency of A(1g)(1) mode and is in good agreement with the AFM result, which indicates that Raman map is an effective method to characterize the thickness difference of ultrathin Bi2Te3 nanoplates.