Compositional effects on the electronic structure of ZnSe1−xSx ternary quantum dots
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(Color online) (a-d) Computed isosurfaces of squared wave functions of the CBM (top) and VBM (bottom) states for pseudo-hydrogen-atom passivated QDs of (a) intrinsic ZnSe, (b) alloyed ZnSe1−xSx (x = 0.25), (c) core/shell ZnSe/ZnS with a partial shell (x = 0.25), and (d) core/shell ZnSe/ZnS with a monolayer-thick shell (x = 0.63). Zn, Se, S, and H atoms are represented by gray, yellow, brown, and white spheres, respectively. (e-g) Valence electron density distribution on a surface plane perpendicular to  (top) and on the surface of a sphere of radius r = 0.5 nm in the core (bottom) of (e) an intrinsic ZnSe QD, (f) an alloyed ZnSe1−xSx TQD (x = 0.36), and (g) a ZnSe/ZnS core/shell TQD (x = 0.36). Zn, Se, S, and H atoms are represented by purple, yellow, green, and blue spheres, respectively. The electron density increases as the color changes from red to yellow to green to blue to purple (top) and from blue to green to yellow to red to purple (bottom). For interpretation of the references to color in this figure, the reader is referred to the online version of this article.
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(Color online) (a-c) Total and partial (atom-projected) DOS in passivated QDs of (a) intrinsic ZnSe, (b) alloyed ZnSe1−xSx, and (c) core/shell ZnSe/ZnS with a partial shell. The total DOS and the individual contributions from Zn, Se, S, and H atoms are represented by black (solid), red (dotted), green (dashed), blue (solid), and yellow/purple (dotted) lines, respectively. In each case, the two vertical red (dashed) lines on the left and right indicate the top of the valence band and the bottom of the conduction band, respectively. (d) Band gap, E g , as a function of the S concentration, x, and its distribution in the alloyed and core/shell TQD configurations. Open squares and open circles are used to denote the band gap for TQDs in alloyed and core/shell configurations, respectively.
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