Electrical properties and ESR of undoped microcrystalline Si with a preferential orientation

Abstract

Electron spin resonance (ESR), conductivity, X-ray diffraction, optical absorption and hydrogen vibrational spectra have been investigated as functions of the substrate temperature, the r.f. power and the hydrogen dilution ratio for undoped microcrystalline Si films. In microcrystalline films deposited at a higher temperature and at a lower r.f. power, a strong preferential orientation has been found. The standard deviation of the orientation from the normal direction on the surface was less than 2·5° at the minimum. A close relation between the observed properties and the degree of preferential orientation has been found. In a microcrystalline film with a preferential orientation, the g value of ESR arising from dangling bonds in the amorphous phase regions was different from that in a film with a random orientation. The coefficient B estimated from the optical absorption for the former films was larger than that for the latter, and a more enhanced conductivity with post-hydrogenation was observed for the former as compared with the latter. Some examinations of the morphology of the amorphous phase in the microcrystalline Si are made.