Computational modeling of quantum-confined impact ionization in Si nanocrystals embedded in SiO2
Date
2007Source Title
Physica E: Low-Dimensional Systems and Nanostructures
Print ISSN
1386-9477
Volume
38
Issue
1-2
Pages
118 - 121
Language
English
Type
ArticleItem Usage Stats
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Abstract
Injected carriers from the contacts to delocalized bulk states of the oxide matrix via Fowler-Nordheim tunneling can give rise to quantum-confined impact ionization (QCII) of the nanocrystal (NC) valence electrons. This process is responsible for the creation of confined excitons in NCs, which is a key luminescence mechanism. For a realistic modeling of QCII in Si NCs, a number of tools are combined: ensemble Monte Carlo (EMC) charge transport, ab initio modeling for oxide matrix, pseudopotential NC electronic states together with the closed-form analytical expression for the Coulomb matrix element of the QCII. To characterize the transport properties of the embedding amorphous SiO2, ab initio band structure and density of states of the α-quartz phase of SiO2 are employed. The confined states of the Si NC are obtained by solving the atomistic pseudopotential Hamiltonian. With these ingredients, realistic modeling of the QCII process involving a SiO2 bulk state hot carrier and the NC valence electrons is provided.
Keywords
Ensamble Monte CarloHigh field transport
Quantum confined impact ionization
Si nanocrystals
Amorphous materials
Charge transfer
Hamiltonians
Ionization
Luminescence
Monte Carlo methods
Quantum confinement
Silica
High field transport
Quantum confined impact ionization
Realistic modeling
Valence electrons
Nanocrystals