Temperature Dependence of ESR Spectra of Doped Amorphous Germanium

Abstract

AbstractThe temperature dependence of g‐value, linewidth, spin density, and spin‐lattice relaxation time are investigated for the three different paramagnetic states in doped amorphous germanium prepared by the glow discharge technique. The dangling bond resonance shows no temperature dependence of g‐value and linewidth. For the resonance due to localized electrons in the conduction band tail the g‐value and particularly the linewidth increase with temperatures above 150 K in highly phosphorus‐doped samples. The increase in linewidth is attributed to the coupling of the spins to electrons in extended states resulting in short spin‐lifetimes. For the resonance of localized holes in the valence band tail, however, g‐value and linewidth decrease above 100 K. In this case the lifetime broadening is overcompensated by a decrease of the g‐spectrum linewidth. From the temperature dependence of the spin density Ns the effective correlation energy U of the three states is derived. In the case of the dangling bonds the value U = 0.1 eV obtained from the energy dependence of Ns is confirmed. The corresponding values for holes and electrons localized in the band tails are 20 to 30 and 5 to 10 meV, respectively. The spin‐lattice relaxation time shows for dangling bonds and localized holes a T−2 temperature dependence down to 5 K which is attributed to two level systems modulating the spin‐orbit coupling. For electrons in the conduction band tail below 15 K a T−7 dependence is observed.