Donor and acceptor concentrations in degenerate InN

A formalism is presented to determine donor (ND) and acceptor (NA) concentrations in wurtzitic InN characterized by degenerate carrier concentration (n) and mobility (μ). The theory includes scattering not only by charged point defects and impurities, but also by charged threading dislocations, of concentration Ndis. For a 0.45-μm-thick InN layer grown on Al2O3 by molecular beam epitaxy, having Ndis=5×1010 cm−2, determined by transmission electron microscopy, n(20 K)=3.5×1018 cm−3 and μ(20 K)=1055 cm2/V s, determined by Hall effect measurements, the fitted values are ND=4.7×1018 cm−3 and NA=1.2×1018 cm−3. The identities of the donors and acceptors are not known, although a comparison of ND with analytical data, and also with calculations of defect formation energies, suggests that a potential candidate for the dominant donor is H.