Infrared spectra of new acceptor levels in boron-doped and gallium-doped silicon

Abstract

Infrared‐absorption measurements have shown the existence of shallower acceptor levels associated with both boron and gallium in silicon. The new spectra correspond to effective‐mass‐like acceptors with optical ionization energies of 37.1±0.3 meV in boron‐doped silicon and 57.0±0.3 meV in gallium‐doped silicon. Similar centers have been previously identified in indium‐ and aluminum‐doped silicon so the defect structure involved seems to be common to the group‐IIIA acceptors in silicon. The presence of this defect explains some of the early discrepancies between the thermally and optically measured activation energies for boron and gallium in silicon.