Ahm. Smets et al., In situ single wavelength ellipsometry studies of high rate hydrogenated amorphous silicon growth using a remote expanding thermal plasma, J APPL PHYS, 88(11), 2000, pp. 6388-6394
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].