Iron-related deep electron traps in epitaxial silicon resolved by Laplace-transform deep level transient spectroscopy

The electronic properties and concentrations of iron-related deep-level defects in n-type epitaxial silicon have been studied by Laplace-transform deep level transient spectroscopy. Three electron traps with activation energies of 392, 455, and 472 meV have been revealed and compared with the known acceptor levels of iron-hydrogen complexes in n-type silicon obtained by using ab initio calculations. The detected electron traps are tentatively attributed to the acceptor levels of the (FesH)(2-/-), (FesH)(0/-) and (HFesH)(0/-) complexes, respectively. The traps concentrations indicate that in as-grown epitaxial layers the (HFesH)(-/0) complexes are predominant defects which effectively decompose at room temperature by releasing one of the two hydrogen atoms. At the elevated temperatures, ranging from 80 degrees C to 240 degrees C, the decomposition rate of these complexes substantially increases. The dissociation of the (FesH)(2-/-) and (FesH)(-/0) complexes also takes place, however the rate of this process is lower than that for the (HFesH)(-/0) defects.