The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. http://dspace-roma3.caspur.it:80 2013-05-19T11:43:37Z 2013-05-19T11:43:37Z De Seta, Monica Capellini, Giovanni Evangelisti, Florestano Busby, Yan http://hdl.handle.net/2307/347 2011-12-22T13:39:36Z 2008-12-31T23:00:00Z

<Title>N-type SiGe heterostructures for THz intersubband transitions</Title> <Authors>De Seta, Monica; Capellini, Giovanni; Evangelisti, Florestano; Busby, Yan</Authors> <Issue Date>2009</Issue Date> <Pages>513-514</Pages> <Abstract>Research on band-gap engineering of Silicon-Germanium heterostructures for the realization of Quantum Cascade (QC) structures emitting in the Terahertz (THz) spectral region has recently attracted a vast interest. While several successful attempts have been reported using hole-based (p-type) intersubband transitions, very few results have been published on systems exploiting electrons (n-type). In this work we present the optical and structural characterization of n-type heterostructures made either of tensely-strained Si (sSi) quantum well (QW) confined between low Ge content Si1-xGex barriers [0.2<x<0.5] or of compressively-strained Ge (sGe) QW confined between high Ge content Si1-xGex barriers [0.8<x<0.9]. The structural and morphological characterizations of the samples have been made by atomic force microscopy (AFM), X-ray photoemission spectroscopy (XPS), transmission electron microscopy (TEM), and Raman spectroscopy. Intersubband transitions have been experimentally investigated by absorption spectroscopy and compared with the theoretical results of a tight-binding model, which provides the electronic band structure of the complete multi quantum well system throughout the whole Brillouin zone.</Abstract>

2008-12-31T23:00:00Z De Seta, Monica Capellini, Giovanni Busby, Yan Evangelisti, Florestano Ortolani, Michele Virgilio, Michele Grosso, Giuseppe Pizzi, Giovanni Nucara, Alessandro Lupi, Stefano http://hdl.handle.net/2307/314 2011-12-22T13:35:27Z 2009-07-31T22:00:00Z

<Title>Conduction band intersubband transitions in Ge/SiGe quantum wells</Title> <Authors>De Seta, Monica; Capellini, Giovanni; Busby, Yan; Evangelisti, Florestano; Ortolani, Michele; Virgilio, Michele; Grosso, Giuseppe; Pizzi, Giovanni; Nucara, Alessandro; Lupi, Stefano</Authors> <Issue Date>2009-08</Issue Date> <Is part of>Applied Physics Letters</Is part of> <Volume>95</Volume> <Pages>051918-051918-3</Pages> <Abstract>In this letter we present the experimental evidence of intersubbandabsorption in the conduction band of compressively strained germaniumquantum wells bounded by Ge-rich SiGe barriers. The measured absorptionenergies are in the terahertz range and are interpreted by means oftight binding calculations which include self-consistent band-bendingand depolarization effects. From the comparison of experimental andnumerical results a conduction band offset along the L line of about120 meV has been estimated for the studied heterostructures.</Abstract>

2009-07-31T22:00:00Z