Density-functional calculation of hyperfine interaction constants of dangling bond and weak bond in GeN and SiN films

Abstract

In order to clarify the origin of electron spin resonance (ESR) signals for amorphous germanium nitride (a-GeN), we have carried out the density-functional calculations of 14N hyperfine interaction constants (HFICs) for Ge-dangling bonds (Ge-DB) and weak Ge–N bonds (deformed N donor). The contribution from the 14N HFICs of Ge-DB to the ESR line width is nearly equal to that of Si-DB. The decrease in the g-value and the line width observed for a-GeN films with the N concentration originates from a decrease in the anisotropy of the g-tensor due to an increase of the N atoms around the Ge-DBs. The 14N HFIC calculated for the weak Ge–N bond with a bond length of 2.4 Å gives 45 G. It is in good agreement with the hyperfine structure in the ESR signal observed for a-GeN without hydrogenation, suggesting that a-GeN films prepared by sputtering include the weak Ge–N bonds.