Direct electron spin resonance determination of dangling bond energies in rf sputtered hydrogenated amorphous silicon

Abstract

The energy positions within the gap of the dangling bond levels are deduced from the variations in intensity of the equilibrium electron spin resonance signal as a function of Fermi level positions in undoped and doped rf sputtered hydrogenated amorphous silicon (a-Si:H). The measurements of optically induced spin signals are used to detect any changes in the dangling bond concentration induced by doping. The results place the singly occupied level at 0.05 eV below the middle of the gap, i.e., at 0.95 eV below the conduction band, in agreement with one of the two values proposed for glow discharge a-Si:H and give an effective correlation energy of +0.3 eV.