Raman studies of boron induced structural changes in amorphous silicon-boron alloys

A new amorphous Si1-xBx alloy with composition of boron x ranging from 0.01 to 0.5 was produced in a low pressure chemical vapor deposition (LPCVD) system. The authors report on Raman scattering experiments on the a-Si1-xBx alloys and specifically monitored the Si-Si TO-like mode at around 480 cm-1 and the TA-like mode at around 130 cm-1. A pronounced broadening of the TO-like band as well as a decrease of the intensity ratio ITO/ITA are observed with an increase of boron concentration in the a-Si1-xBx alloys. Based on the Raman spectra, the structural changes induced by boron incorporation in the a-Si network are discussed in the conceptual framework of the continuum random network (CRN) model. The authors conclude that boron incorporation enhances the structural disorder and induces topological changes in the amorphous network