Open Access Nano Express

Room-temperature efficient light detection by amorphous Ge quantum wells

Salvatore Cosentino1*, Maria Miritello1, Isodiana Crupi1, Giuseppe Nicotra2, Francesca Simone1, Corrado Spinella2, Antonio Terrasi1 and Salvatore Mirabella1

Author affiliations

1 MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, Catania 95123, Italy

2 IMM-CNR, VIII strada 5, Catania 95121, Italy

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Citation and License

Nanoscale Research Letters 2013, 8:128  doi:10.1186/1556-276X-8-128

Published: 16 March 2013

Abstract

In this work, ultrathin amorphous Ge films (2 to 30 nm in thickness) embedded in SiO2 layers were grown by magnetron sputtering and employed as proficient light sensitizer in photodetector devices. A noteworthy modification of the visible photon absorption is evidenced due to quantum confinement effects which cause both a blueshift (from 0.8 to 1.8 eV) in the bandgap and an enhancement (up to three times) in the optical oscillator strength of confined carriers. The reported quantum confinement effects have been exploited to enhance light detection by Ge quantum wells, as demonstrated by photodetectors with an internal quantum efficiency of 70%.

Keywords:
Germanium; Nanostructures; Light absorption; Quantum confinement effect