Effects of substrate temperature on structural and electrical properties of SiO2-matrix boron-doped silicon nanocrystal thin films

Abstract

In this work, silicon-rich SiO2 (SRSO) thin films were deposited at different substrate temperatures (Ts) and then annealed by rapid thermal annealing to form SiO2-matrix boron-doped silicon-nanocrystals (Si-NCs). The effects of Ts on the micro-structure and electrical properties of the SiO2-matrix boron-doped Si-NC thin films were investigated using Raman spectroscopy and Hall measurements. Results showed that the crystalline fraction and dark conductivity of the SiO2-matrix boron-doped Si-NC thin films both increased significantly when the Ts was increased from room temperature to 373K. When the Ts was further increased from 373K to 676K, the crystalline fraction of 1373K-annealed thin films decreased from 52.2% to 38.1%, and the dark conductivity reduced from 8×10−3 S/cm to 5.5×10−5S/cm. The changes in micro-structure and dark conductivity of the SiO2-matrix boron-doped Si-NC thin films were most possibly due to the different amount of SiO4 bond in the as-deposited SRSO thin films. Our work indicated that there was an optimal Ts, which could significantly increase the crystallization and conductivity of Si-NC thin films. Also, it was illumined that the low-resistivity SiO2-matrix boron-doped Si-NC thin films can be achieved under the optimal substrate temperatures, Ts.