550 research outputs found
Influence of quantum confinement on the ferromagnetism of (Ga,Mn)As diluted magnetic semiconductor
We investigate the effect of quantum confinement on the ferromagnetism of
diluted magnetic semiconductor GaMnAs using a combination of
tight-binding and density functional methods. We observe strong majority-spin
Mn -As hybridization, as well as half metallic behavior, down to sizes
as small as 20 \AA in diameter. Below this critical size, the doped holes are
self-trapped by the Mn-sites, signalling both valence and electronic
transitions. Our results imply that magnetically doped III-V nanoparticles will
provide a medium for manipulating the electronic structure of dilute magnetic
semiconductors while conserving the ferromagnetic properties and even enhancing
it in certain size regime.Comment: 4 pages, 3 figure
Simultaneous control of nanocrystal size and nanocrystal-nanocrystal separation in CdS nanocrystal assembly
We report an easy, one pot synthesis to prepare ordered CdS nanocrystals with varying inter-particle separation and characterize the particle separation using x-ray diffraction at low and wide angles
Electronic structure of and Quantum size effect in III-V and II-VI semiconducting nanocrystals using a realistic tight binding approach
We analyze the electronic structure of group III-V semiconductors obtained
within full potential linearized augmented plane wave (FP-LAPW) method and
arrive at a realistic and minimal tight-binding model, parameterized to provide
an accurate description of both valence and conduction bands. It is shown that
cation sp3 - anion sp3d5 basis along with the next nearest neighbor model for
hopping interactions is sufficient to describe the electronic structure of
these systems over a wide energy range, obviating the use of any fictitious s*
orbital, employed previously. Similar analyses were also performed for the
II-VI semiconductors, using the more accurate FP-LAPW method compared to
previous approaches, in order to enhance reliability of the parameter values.
Using these parameters, we calculate the electronic structure of III-V and
II-VI nanocrystals in real space with sizes ranging upto about 7 nm in
diameter, establishing a quantitatively accurate description of the band-gap
variation with sizes for the various nanocrystals by comparing with available
experimental results from the literature.Comment: 28 pages, 8 figures, Accepted for publication in Phys. Rev.
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