Naslov
The DC conductivity and structural ordering of thin silicon films at the amorphous to nano-crystalline phase transition

Autori
Gracin, Davor ; Etlinger, Božidar ; Juraić, Krunoslav ; Gajović, Andreja ; Dubček, Pavo ; Bernstorff, Sigrid

Izvornik
Vacuum (0042-207X) 82 (2007), 2; 205-208

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
nanocrystalline silicon; GISAXS; Raman; DC conductivity

Sažetak
Thin silicon films were deposited by PECVD method using standard 13.6 MHz (RF) gas discharge in silane gas, diluted by hydrogen. The deposition condition was kept constant from sample to sample for all parameters except for the degree of dilution that was varied from low values that produces amorphous layers up to the high dilution that resulted in high degree of crystalline fraction. The structural properties of samples were analysed by Raman and GISAXS spectroscopy while DC dark conductivity was measured by standard methods. The ratio of areas under corresponding TO phonon peaks in Raman was taken as a ratio between crystal and amorphous volume fraction while the shift of TO peak position was used for estimation of crystal size. By increasing working gas dilution, crystalline fraction grew from 0 to 40% and the average individual size of crystals increased from 2 to 10 nm. The size of "particles", estimated upon GISAX spectra by using Guinier approximation, varied from 2 to 4 nm. For lower working gas dilution, the "particles" detected by GISAXS were spherically symmetric and showed no difference between near surface and "bulk” of the film. For higher dilution, the particles became asymmetric and larger when closer to the surface, which indicates columnar growth. The DC dark conductivity increased exponentially with crystalline fraction, except for very low crystal to amorphous volume ratio where the conductivity was larger, probably due to better ordering of amorphous phase when closer to the amorphous to crystalline transition.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA