Diffusion of indium in single crystal zinc oxide: a comparison between group III donors

Abstract

Dopant diffusion of indium (In) in single crystal zinc oxide is studied by secondary ion mass spectrometry and is interpreted using a reaction-diffusion model that invokes predictions from density functional theory (DFT). An apparent activation energy of 2.2 eV is obtained for the diffusion of In, when the local Fermi-level position is about 0.2 eV below the conduction band edge. The diffusion of In is found to be significantly faster that that reported for the other group III donors, aluminum and gallium, with several orders of magnitude higher effective diffusivities, that can be assigned to a lower migration barrier for the diffusion of In. Furthermore, our results reveal self-consistency in previous DFT results of defect formation-and migration energies. From this, the diffusion of In is suggested to occur through mobile charged zinc vacancies -V Zn 2 that form intermediate mobile ( V In Zn Zn ) − pairs. The pairs in turn dissociate rather readily at the studied temperatures (850 °C-1150 °C), which results in distinct and abrupt diffusion fronts for the In depth distribution profiles.

Properties of Donor Qubits in ZnO Formed by Indium-Ion Implantation

“…These observed changes in the integrated PL intensity indicate that the entire volume of material probed with nearband gap excitation (λ exc = 360 nm) is affected by the In implantation. This does not necessarily mean the probing depth is only the 200 nm depth of implanted In ions, because intrinsic defects created during implantation could diffuse deeper into the material during annealing [36][37][38].…”

Heavily Doped Zinc Oxide with Plasma Frequencies in the Telecommunication Wavelength Range

“…a) Solid-solubility-limit as a function of temperature for n-type dopants (Ga, Al, In) in single-crystalline ZnO, using data taken from references. [22][23][24] b) Dopant diffusion lengths for Ga, Al, and In in ZnO at 900 °C as a function of annealing time. [23,25,26] The dashed orange lines indicate typical annealing times for furnace annealing (FA) and laser annealing (LA).…”

“…Their modeling of the measured Ga diffusion profiles revealed that the dominant diffusion mechanism is consistent with zinc (Zn) vacancy (V Zn ) mediation via the formation and dissociation of Ga Zn V Zn complexes with substitutional Ga at the Zn sub-lattice (Ga Zn ). [22] The temperature-dependent SSL of Ga, aluminum (Al), and indium (In) in ZnO was determined by Sky et al with a reactiondiffusion-type model, [22][23][24] which is based on Fickian diffusion plus a nonlinear reaction term. More theoretical background can be found in refs.…”

“…[23,25] Figure 1a depicts the SSL for the three n-type dopants in ZnO, Ga, Al, and In, as a function of temperature. [22][23][24] Ga has the highest SSL over a wide temperature range, which makes it the most promising dopant for ZnO plasmonics. This is mainly connected to the small tetrahedral covalent radius and the low formation energy of Ga 2 O 3 compared to those of Al 2 O 3 and In 2 O 3 .…”

Effects of Post-Annealing on the Properties of ZnO:Ga Films with High Transparency (94%) and Low Sheet Resistance (29 Ω/square)

“…The most common material in TCOs is indium tin oxide (ITO). However, efforts are being made to find alternative materials with low resistivity and high transmittance to replace ITO because of the high cost of indium and the diffusion problem [1,2]. As the device becomes smaller, the electrode thickness must be as thin as possible to maintain low resistance.…”