Prospects of enhancement of p-type conductivity in ZnO nanowires

Abstract

Semiconductor nanowires, are believed to act as key elements in future nanoscaled optoelectronic devices, as they offer intriguing electrical and optoelectronic properties. However, the future of any semiconductor nanowire technology will essentially rely on their doping capability. The availability of both n- and p-type semiconductors is important for the realization of nanowire-based electronics. Wide band gap semiconductors, such as ZnO, suffer from doping polarity. They can be easily doped n- (or p-type) at the expense of difficulties for doping of opposite type. Space confinement changes donor and acceptor ionization energies; the main factor that makes difficult to obtain n- or p-conductivity is formation of compensating defects. Compensating processes are strongly affected by electronic structure of system: band gap, ionization energies of donors, acceptors and their compensation centers. In the present paper we calculated energy levels of electron bound to Coulomb impurity that is incorporated in semiconductor nanowire. Effect of dielectric confinement on ionization energies are considered as well. For analyzing perspectives of suppressing processes of compensation and achieving low ohmic p-conductivity Kröger method of quasi-chemical equations is used.