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First‐principles calculation and X‐ray absorption fine structure analysis of Fe doping mechanism for semi‐insulating GaN growth on GaAs substrates

In order to fabricate an Fe‐doped semi‐insulating (SI) GaN substrate by hydride vapor phase epitaxy (HVPE) using (111)A GaAs as a starting substrate, the Fe doping mechanism was investigated by two approaches: first‐principles calculation and X‐ray absorption fine structure (XAFS) measurements. First‐principles study clarified that Fe and As atoms are substituting for the Ga and N atoms in the wurtzite GaN lattice, respectively. In addition, incorporation of Fe in GaN was found to be hindered by adjacent As in the N site. XAFS analysis performed for an Fe‐doped SI GaN substrate, obtained by protecting backside of the GaAs substrate, showed that the Fe atoms are substituting for the Ga site in GaN. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)