1. THz intersubband absorption in n-type Si 1−x Ge x parabolic quantum wells
- Author
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David Stark, Chiara Ciano, Leonetta Baldassarre, Michele Virgilio, Michele Montanari, Cedric Corley, Luca Persichetti, Luciana Di Gaspare, Monica De Seta, Giovanni Capellini, Giacomo Scalari, Michele Ortolani, Montanari, Michele, Ciano, Chiara, Persichetti, Luca, Corley, Cedric, Baldassarre, Leonetta, Ortolani, Michele, Di Gaspare, Luciana, Capellini, Giovanni, Stark, David, Scalari, Giacomo, Virgilio, Michele, and De Seta, Monica
- Subjects
010302 applied physics ,Range (particle radiation) ,Settore FIS/03 ,Materials science ,Physics and Astronomy (miscellaneous) ,Electronic correlation ,Terahertz radiation ,Doping ,silicon-germanium alloys ,02 engineering and technology ,Electron ,Chemical vapor deposition ,quantum wells, terahertz, silicon-germanium alloys ,FLASH ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,terahertz ,quantum wells ,0103 physical sciences ,THz spectroscopy ,0210 nano-technology ,Absorption (electromagnetic radiation) ,Quantum well - Abstract
High-quality n-type continuously graded Ge-rich Si1−xGex parabolic quantum wells with different doping level were grown by using ultrahigh-vacuum chemical vapor deposition on Si(001) substrates. A thorough structural characterization highlights an ideal parabolic compositional profile. THz intersubband absorption has been investigated in modulation-doped samples and samples directly doped in the wells. The comparison of experimental absorption data and theoretical calculations allowed us to quantify the impact of electron correlation effects on the absorption resonances in the different doping conditions and for electron sheet densities in the (1÷6)×1011 cm−2 range. A single optical resonance is present in modulation doped samples. Its peak energy and line-shape is independent of temperature-induced variations of the electron distribution in the subbands up to 300 K, in agreement with the generalized Kohn theorem. This achievement represents a relevant step-forward for the development of CMOS compatible optoelectronic devices in the THz spectral range, where thermal charge fluctuations play a key role.
- Published
- 2021
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