W. P. Kirk | Searcharxiv

arXiv2009

Generalized band anti-crossing model for highly mismatched semiconductors applied to BeSe$_{x}$Te$_{1 - x}$

We report a new model for highly mismatched semiconductor (HMS) alloys. Based on the Anderson impurity Hamiltonian, the model generalizes the recent band anti-crossing (BAC) model, which successfully explains the band bowing in highly mismatched semiconductors. Our model is formulated in empirical tight-binding (ETB) theory and uses the so called sp$^{3}$s* parameterization. It does not need extra parameters other than bulk ones. The model has been applied to BeSe$_{x}$Te$_{1 - x}$ alloy. BeTe and BeSe are wide-band gap and highly mismatched semiconductors. Calculations show large band bowing, larger on the Se rich side than on the Te rich side. Linear interpolation is used for an arbitrary concentration $x$. The results are applied to calculation of electronic and optical properties of BeSe$_{0.41}$Te$_{0.59}$ lattice matched to Si in a superlattice configuration.

cond-mat.other↗

arXiv2002

Improved Light Absorption by Quantum Confinement and Band Folding: Enhanced Efficiency in Silicon Based Solar Cells

The improvement of light absorption in Si/BeSe$_{0.41}$Te$_{0.59}$ heterostructures for solar cell applications is studied theoretically. First, using simple approaches we found that light absorption could be improved in a single (uncoupled) quantum well with a thickness up to 20 Å. Second, by semiempirical tight-binding methods we calculated the electronic structure and optical properties of various (Si$_{2})_{n}$/(BeSe$_{0.41}$Te$_{0.59})_{m}$ [001] superlattices. Two bands of interface states were found in the band gap of bulk Si. Our calculations indicate that the optical edges are close to the fundamental band gap of bulk Si and the transitions are optically allowed.

cond-mat.mes-hall↗