Theoretical Aspects of Porous Silicon
In this work, we study the electronic and optical properties of porous silicon (PS) using a supercell model, where an sp 3 s* tight-binding Hamiltonian is used and empty columns of atoms are produced in an otherwise perfect silicon structure, passivated with hydrogen atoms. As it is considered that quantum confinement is one of the causes of the optoelectronic properties of PS, we perform a detailed analysis of the consequences of confinement on its band structure. Our results show that the band gap broadens and the minimum of the conduction band shifts towards the gamma point as the porosity is increased. The polarized light absorption study shows that the optically active zone in the reciprocal space broadens significantly due to disorder, relaxing the k-wavevector selection rule. We found that introducing non-vertical interband transitions to take into account the PS disordered nature, we get a very good agreement with experimental data.
KeywordsPorous Silicon Oscillator Strength Dielectric Function Quantum Confinement Porous Silicon Sample
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