Maximization of hydrogen incorporation on a-Si:H using optical emission spectroscopy

Abstract

The use of hydrogenated amorphous silicon, a-Si:H, for improving heterojunction solar cell efficiency and decreasing cost has found increasing interest in recent years. Hydrogen incorporation in thin films of amorphous silicon is crucial for obtaining semiconductor quality because it passivates Si dangling bonds in the structure. In the present work the plasma optical emission during film growth by DC magnetron sputtering in Ar-H plasma was used to maximize hydrogen incorporation the a-Si and the effects of hydrogenation were evaluated, as part of a systematic investigation of different vapor a-Si:H deposition processes, physical and chemical. The experiments were performed using the Magnetron Sputtering technique varying the DC power and Ar-H gas rates. The grown films were characterized by Raman scattering, FT-IR spectroscopy and AFM. The results show that maximizing the plasma emission from Si-H species enhances hydrogen incorporation in amorphous films. The results also show the possibility of automatically controlling plasma composition for optimum hydrogen incorporation through optical emission spectroscopy (OES).