Auger line-shape analysis of the structure of hydrogenated amorphous silicon

Calculated Si $L_{23}\mathrm{VV}$ Auger line shapes are presented for five realistic structural models of hydrogenated amorphous silicon ($a$-Si: H), based on the local-electronic-structure calculations of Ching, Lam, and Lin. The calculated Auger spectra show peak shifts of the main Si $L_{23}{M}_{23}{M}_{23}$ ($\mathrm{pp}$) transition up to 6 eV, and distinct line shapes dependent on the H-bonding configuration. Comparison of the calculated spectra to the experimental work of Allie et al. on sputtered $a$-Si: H clearly shows an expected increased prominence of the $L_{23}{M}_1{M}_{23}$ ($\mathrm{sp}$) term relative to the $L_{23}{M}_{23}{M}_{23}$ ($\mathrm{pp}$) term, due to the Si $3s$ localization upon hydrogenation. The results indicate that valuable structural information is available from Auger spectroscopy for this interesting system.