Advantage of In- over N-polarity for disclosure of p-type conduction in InN:Mg

Abstract

We have measured thermoelectric power in two series of polar InN:Mg samples with wide range of Mg content having In-as well as N-growth polarities. We have observed essential differences between both polarities: In the "p-type window" centered at about 1 Â 10 19 cm À3 of [Mg], reported recently, the thermoelectric power changed its sign from n to p-type, only for In-growth polarity samples. These results have been confirmed by the so-called mobility spectrum analysis. It strongly supports the suggestion that In-growth polarity is more propitious to p-type conduction in InN:Mg than the N one. V C 2014 AIP Publishing LLC. [http://dx.

Extending group‐III nitrides to the infrared: Recent advances in InN

“…A few important observations are described: (i) The structural parameters and extended defect densities are not severely affected by Mg concentrations in the range of 10 18 –10 19 cm −3 ; (ii) for highly Mg doped samples (Mg concentration >1.8 × 10 20 cm −3 ), the surface becomes rough, and screw dislocation densities increase; (iii) Mg incorporation induces stacking faults, which lead to the formation of zinc blende (ZB) structure for highly Mg doped samples; (iv) Mg was found to increase a ‐ and decrease c ‐lattice parameters, due to the Mg‐induced biaxial tensile strain. In addition, recent studies further suggest that the polarity has a significant influence on the p ‐type doping in InN epilayers . Shown in Fig.…”

“…Room temperature Seebeck coefficients for In‐polar and N‐polar samples with different Mg concentrations .…”

“…To date, the progress of InN‐based optoelectronic devices has been fundamentally limited by the difficulty in p ‐type doping. Only magnesium (Mg), with an activation energy of ∼60 meV, has been shown to dope InN p ‐type, although other dopants such as manganese (Mn) and zinc (Zn) have also been suggested . In what follows, the properties of Mg‐doped InN epilayers and the first direct measurement of p ‐type conduction in InN by using nanowire structures are described.…”

“…The measured low 10 13 cm −3 approaches to that of intrinsic InN at room temperature. The presence of Mg acceptors and p ‐type window has been demonstrated in InN epilayers . The direct measurement of p ‐type conduction in InN epilayers, however, has been limited by the presence of surface electron accumulation on the grown surfaces.…”

Electrical properties of surface and interface layers of the N- and In-polar undoped and Mg-doped InN layers grown by PA MBE

“…However, its possible contribution to the total InN conductivity was not separately studied, and it is usually assumed that the surface and interface layers have analogous transport parameters which are determined only by the donor-type defects [16]. Additionally, it was assumed that the contribution of the 2D surface layer is smaller in case of In-polar InN films in comparison with N-polar ones [17], however no experimental comparison of the In-and N-polar InN films has been made to date. Meanwhile, study of the effects of masking the bulk InN electrical properties by the different conducting channels, as well as the ways to minimize these parasitic contributions are important in terms of future electronic and optoelectronic applications of InN and In-rich InGaN.…”