Novel Method for the Activation of Acceptor Dopant in AlN Introducing Localized Band by Isoelectronic Dopant

Abstract

ABSTRACTIn this study we propose a novel method to increase hole concentration introducing isovalent substitutional dopant into a p-type nitride semiconductor. Acceptor dopant in nitride semiconductors makes deep acceptor level (>100 meV) and generates few hole carriers into the valence band because of large electron affinity of N.In contrast to this, substitution of isovalent group-V atoms (P, As and Sb) that has smaller affinity than N makes a localized group-V band upward the valence band maximum (VBM). When both acceptor and isovalent group-V atoms are incorporated into nitride semiconductor, holes can be drastically activated by isovalent atoms, and can easily move in the group-V band. We have also investigated this material, Mg-doped AlN:V (V=P, As or Sb), using first-principles pseudopotential method. As a calculation result, substitiution of P and As makes localized group-V band upward the VBM of AlN, and moreover this can be adjusted the VBM of GaN. The Mg incorporation into AlN:V as an acceptor dopant drastically decreases the Fermi level (ΔEF=-0.10 eV), that is, hole concentration can be drastically raised by the group-V band. Consequently novel p-type material with isovalent dopant can be a candidate to efficiently inject hole current into the VBM of GaN.