Stable Photogenerated Carriers in Magnetic Semiconductor Nanocrystals

Abstract

We report the preparation and investigation of charged colloidal Co2+:ZnO and Mn2+:ZnO nanocrystals. Although both charged and magnetically doped colloidal semiconductor nanocrystals have been reported previously, colloidal charged and magnetically doped semiconductor nanocrystals as described herein have not. Conduction band electrons were introduced into colloidal ZnO diluted magnetic semiconductor (DMS) nanocrystals photochemically, and the resulting TM2+-e-CB interactions were observed by electron paramagnetic resonance spectroscopy (TM2+ = Co2+ or Mn2+). This new motif of colloidal charged magnetic semiconductor nanocrystals reveals attractive new opportunities for studying spin effects in DMS nanostructures relevant to proposed spintronics technologies.

Room-Temperature Electron Spin Dynamics in Free-Standing ZnO Quantum Dots

“…Freestanding ZnO QDs capped with trioctylphosphine oxide (TOPO) and suspended in toluene were prepared, charged, and characterized as described previously [6,7]. Conduction band electrons (e ÿ CB ) were generated by UV irradiation in the presence of ethanol, a hole scavenger [8], under rigorously anaerobic conditions [7].…”

“…Conduction band electrons (e ÿ CB ) were generated by UV irradiation in the presence of ethanol, a hole scavenger [8], under rigorously anaerobic conditions [7].…”

Modulation of the electron transfer processes in Au–ZnO nanostructures

“…The transfer of electrons in the Au to ZnO direction, after selective irradiation of the nanostructures in the visible region, was confirmed by direct observation of conduction band electrons in ZnO by EPR spectroscopy, [26][27][28] under anaerobic conditions. Thus, we definitively probe that by modulating the excitation wavelength the electron flow direction can be switched, which is interesting for the development of logical devices.…”

“…Also, for a given nanoparticle diameter, g values increase with <n>, the average number of electrons per ZnO nanocrystal. 26,27 Taking into account the combined facts we considered that the change from g = 1.9655 to 1.9623, that occurs as a result of the irradiation process, reflects that the number of electrons per particle is low, and that they preferentially reside in larger sized particles which favour electron delocalization. 24 Irradiated samples also show the emergence of a weak signal centred at g = 2.0045.…”

First-principles calculations of lattice-strained core-shell nanocrystals

“…By varying the chemistry and thickness of each region, one can tune these nanocrystals to possess a wide range of properties, leading to applications in diverse areas such as optoelectronics, 1 biolabelling and sensing, 2 light emitting diodes, 3 solar cells, 4 photovoltaic materials, 5 spintronics, 6,7 and lasers 8 using different growth techniques. [9][10][11][12][13] .…”