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High‐Pressure Photoluminescence Studies of Pseudomorphic Si 1– y C y /Si MQW Structures
Author(s) -
Liu Z.X.,
Goñi A.R.,
Manz C.,
Syassen K.,
Brunner K.,
Eberl K.
Publication year - 2000
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200005)219:1<103::aid-pssb103>3.0.co;2-k
Subject(s) - materials science , photoluminescence , condensed matter physics , hydrostatic pressure , direct and indirect band gaps , band gap , phonon , band offset , silicon , exciton , pressure coefficient , optoelectronics , physics , valence band , thermodynamics , mechanics
We have performed photoluminescence (PL) investigations of pseudomorphic Si 1– y C y /Si ( y = 0.45, 1.05, and 1.62%) multiple quantum well (MQW) structures under hydrostatic pressure (0 to 8 GPa) and at low temperatures (10 to 70 K). The main MQW‐related emission, at energies below the Si band gap, consists of bound and free exciton no‐phonon lines and related Si transverse‐optic phonon replicas. All MQW‐related PL peaks shift to lower energy with increasing pressure at a rate characteristic for Γ–X indirect transitions in tetrahedral semiconductors. The total band offset and the activation energies for decay of the free and bound exciton emission increase slightly with pressure as a result of the larger negative band gap pressure coefficient of the strained pseudomorphic Si 1– y C y layers compared to pure silicon. A separation of biaxial strain effects on the conduction and valence band near‐gap states in the pseudomorphic Si 1– y C y layers ( y ≤ 0.02) on Si indicates a decrease of the intrinsic Si 1– y C y band gap which corresponds to that of pure silicon compressed to the lattice constant of the alloy. From this a type‐I band alignment with electrons and light holes localized in the SiC layers is inferred. This assignment is consistent with the dependence of PL‐peak intensities and energies on excitation power, temperature and pressure.