In situ single wavelength ellipsometry studies of high rate hydrogenated amorphous silicon growth using a remote expanding thermal plasma

An in situ single wavelength HeNe rotating ellipsometry study of high rate (similar to 80 Angstrom s(-1)) hydrogenated amorphous silicon (a-Si:H) depo sition using an expanding thermal plasma is presented. An optical growth mo del is used to simulate the measured ellispometric trajectories similar to models used for low rate a-Si:H growth in the literature. The in situ growt h at high growth rates was studied as function of the substrate temperature . The refractive index n (at 632.8 nm) increases with increasing temperatur e corresponding to an increase in the density of the films. The in situ ext inction coefficient k (at 632.8 nm) increases with increasing substrate tem perature due to a smaller optical band gap and due to an increase in indire ct absorption. It is shown that the ellipsometry setup in combination with optical modeling enables us to monitor the surface roughness evolution duri ng deposition and to obtain the dynamic scaling exponent beta for postiniti al growth. (C) 2000 American Institute of Physics. [S0021-8979(00)09123-4].