Effects of boron doping on solid phase crystallization of in situ doped amorphous Silicon thin films prepared by electron beam evaporation

Abstract

In this work, we studied solid-phase crystallization of boron-doped non-hydrogenated amorphous Si films fabricated by electron beam evaporation equipped with effusion cells (e-Beam EC) on silicon nitride coated glass substrates. We investigated the effect of boron doping on the crystallization kinetics through a series of experiments with different boron doping concentrations controlled by the effusion cell temperature. We employed Raman spectroscopy, time-of-flight secondary ion mass spectroscopy, grazing incidence X-ray diffraction, Hall Effect measurement and X-ray photoelectron spectroscopy (XPS) to understand the structural and electrical variations with regard to B doping and process conditions. We found that the stress in the poly-Si thin film increases when the B concentration increases from 1018 to 1020 atoms/cm3, reaching a value of to 1087.5 MPa. We also studied the chemical environment around the B atoms by comparing the B1s binding energies in XPS measurements, which revealed that B–Si coordination does not change upon crystallization. The electrical effect of boron doping was observed in a drastic drop in resistivity from orders of 102 to the 10−3 Ω.cm. Moreover, we found that an increase in boron doping concentration leads to a higher crystallization rate of non-hydrogenated amorphous silicon thin films prepared by e-Beam EC.