Even though intrinsic semiconductor nanowires have already extraordinary optical properties, doping with optically active impurities significantly expands the potpourri of optoelectronic applications, such as for nanowire lasers or single photon emitters. This feature article therefore supplies a snapshot of the most recent progress on the structural and optical properties of transition metal and rare earth element doped zinc oxide (ZnO) nanowires using ion beam doping. Here, ion implantation is advantageous, as concurrent defect generation and diffusion upon subsequent annealing allows the formation of defect complexes. This scenario is in many cases even inevitable for the optical activation of the intra‐shell luminescence of the implanted impurities, as density functional theory calculations demonstrate. Finally, this article also provides the optimum preparation conditions for intense optical activity and a review on the specific luminescence properties of various optical centers in ZnO nanowires.
In this work we investigate the electronic properties of mercaptocarboxylic acids with several carbon chain lengths adsorbed on ZnO-(10-10) surfaces via density functional theory calculations using semi-local and hybrid exchange-correlation functionals.Amongst the investigated structures, we identify the monodentate adsorption mode to be stable. Moreover, this mode introduces optically active states in the ZnO gap, is further confirmed by the calculation of the dielectric function at PBE0 and TD-PBE0 levels. One interesting finding is that adsorption mode and the dielectric properties of the hybrid system are both rather insensitive to the chain length, since the acceptor 1 arXiv:1810.02256v1 [cond-mat.mtrl-sci] 4 Oct 2018 molecular state is very localized on the sulphur atom. This indicates that even small molecules can be used to stabilize ZnO surface and to enhance its functionality for opto-electronic applications.
Adsorption of small ligands on semiconductor surfaces is a possible route to modify these surfaces so that they can be used in biosensing and optoelectronic devices. In this work we perform density‐functional theory calculations of electronic and optical properties of small ligands on GaN‐100) surfaces. From the investigated anchor groups we show that thiol groups introduce states in the band gap of GaN surfaces, although not optically active. Our results open the possibility for further surface modification to enhance the optical properties of GaN non‐polar surfaces.
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