Real-time study of HWCVD a-Si:H film growth using optical second harmonic generation spectroscopy

Hydrogenated amorphous silicon (a-Si:H) thin films deposited by HWCVD have been investigated by the surface/interface-sensitive nonlinear technique of optical second harmonic generation (SHG). In situ spectral SHG scans have revealed two resonance peaks at ∼ 1.2 eV and ∼ 1.45 eV corresponding with electronic states (e.g., Si dangling bonds, Si–Si strained bonds) at the surface/interface of the a-Si:H with an isotropic distribution. The data are compared to SHG results obtained ex situ for a-Si:H films deposited by an rf plasma. The first real-time SHG experiments during HWCVD a-Si:H film growth are presented.