Abstract

In this work, we report on the competition between two-step two photon absorption, carrier recombination,and escape in the photocurrent generation mechanisms of high quality InAs/GaAs quantumdot intermediate band solar cells. In particular, the different role of holes and electrons ishighlighted. Experiments of external quantum efficiency dependent on temperature and electricalor optical bias (two-step two photon absorption) highlight a relative increase as high as 38% at10K under infrared excitation. We interpret these results on the base of charge separation by phononassisted tunneling of holes from quantum dots. We propose the charge separation as an effectivemechanism which, reducing the recombination rate and competing with the other escapeprocesses, enhances the infrared absorption contribution. Meanwhile, this model explains why thermalescape is found to predominate over two-step two photon absorption starting from 200 K,whereas it was expected to prevail at lower temperatures (70 K), solely on the basis of the relativelylow electron barrier height in such a system. VC 2016 AIP Publishing LLC.

Autore Pugliese

• Cola Adriano , Creti' Arianna , Montagna Giovanni , Lomascolo Mauro , Passaseo Adriana Grazia , Tasco Vittorianna

Tutti gli autori

• A. Creti; V. Tasco; A. Cola; Montagna; Tarantini; A. Salhi; A. Al-Muhanna; A. Passaseo; M. Lomascolo

Titolo volume/Rivista

Applied physics letters

Anno di pubblicazione

2016

ISSN

0003-6951

ISBN

Non Disponibile

Numero di citazioni Wos

Nessuna citazione

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Numero di citazioni Scopus

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Settori ERC

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Codici ASJC

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