Abstract
We propose and analyze a physical mechanism for photogeneration of multiexcitons by single photons (carrier multiplication) in semiconductor nanocrystals, which involves intraband optical transitions within the manifold of biexciton states. In this mechanism, a virtual biexciton is generated from nanocrystal vacuum by the Coulomb interaction between two valence-band electrons, which results in their transfer to the conduction band. The virtual biexciton is then converted into a real, energy-conserving biexciton by photon absorption on an intraband optical transition. The proposed mechanism is inactive in bulk semiconductors as momentum conservation suppresses intraband transitions. However, it becomes highly efficient in the case of zero-dimensional nanocrystals, where quantum confinement results in relaxation of momentum conservation, which is accompanied by the development of strong intraband absorption. Our calculations show that the efficiency of the carrier multiplication channel mediated by intraband optical transitions can be comparable to or even greater than that for impact-ionization-like processes mediated by interband transitions.
| Original language | English |
|---|---|
| Article number | 125321 |
| Journal | Physical Review B - Condensed Matter and Materials Physics |
| Volume | 76 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - Sep 25 2007 |
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ASJC Scopus subject areas
- Condensed Matter Physics
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Carrier multiplication in semiconductor nanocrystals via intraband optical transitions involving virtual biexciton states. / Rupasov, Valery I.; Klimov, Victor I.
In: Physical Review B - Condensed Matter and Materials Physics, Vol. 76, No. 12, 125321, 25.09.2007.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Carrier multiplication in semiconductor nanocrystals via intraband optical transitions involving virtual biexciton states
AU - Rupasov, Valery I.
AU - Klimov, Victor I
PY - 2007/9/25
Y1 - 2007/9/25
N2 - We propose and analyze a physical mechanism for photogeneration of multiexcitons by single photons (carrier multiplication) in semiconductor nanocrystals, which involves intraband optical transitions within the manifold of biexciton states. In this mechanism, a virtual biexciton is generated from nanocrystal vacuum by the Coulomb interaction between two valence-band electrons, which results in their transfer to the conduction band. The virtual biexciton is then converted into a real, energy-conserving biexciton by photon absorption on an intraband optical transition. The proposed mechanism is inactive in bulk semiconductors as momentum conservation suppresses intraband transitions. However, it becomes highly efficient in the case of zero-dimensional nanocrystals, where quantum confinement results in relaxation of momentum conservation, which is accompanied by the development of strong intraband absorption. Our calculations show that the efficiency of the carrier multiplication channel mediated by intraband optical transitions can be comparable to or even greater than that for impact-ionization-like processes mediated by interband transitions.
AB - We propose and analyze a physical mechanism for photogeneration of multiexcitons by single photons (carrier multiplication) in semiconductor nanocrystals, which involves intraband optical transitions within the manifold of biexciton states. In this mechanism, a virtual biexciton is generated from nanocrystal vacuum by the Coulomb interaction between two valence-band electrons, which results in their transfer to the conduction band. The virtual biexciton is then converted into a real, energy-conserving biexciton by photon absorption on an intraband optical transition. The proposed mechanism is inactive in bulk semiconductors as momentum conservation suppresses intraband transitions. However, it becomes highly efficient in the case of zero-dimensional nanocrystals, where quantum confinement results in relaxation of momentum conservation, which is accompanied by the development of strong intraband absorption. Our calculations show that the efficiency of the carrier multiplication channel mediated by intraband optical transitions can be comparable to or even greater than that for impact-ionization-like processes mediated by interband transitions.
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U2 - 10.1103/PhysRevB.76.125321
DO - 10.1103/PhysRevB.76.125321
M3 - Article
VL - 76
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
SN - 1098-0121
IS - 12
M1 - 125321
ER -