1971/04/15 by Lucien D. Laude, L.D. Laude, Fred H. Pollak +2 · 4 citations
Physics and Astronomy · Materials Science · #Semiconductor Quantum Structures and Devices #Quantum and electron transport phenomena #Silicon Nanostructures and Photoluminescence
paper · doi:10.1103/physrevb.3.2623
We have measured the stress dependence of the indirect exciton spectrum of silicon at 77\ifmmode^∘\else\textdegree\fiK, for static uniaxial compression along the [111], [001], and [110] directions with light polarized parallel and perpendicular to the stress direction, using wavelength modulation. The high stresses reached in this work (X=1.8\ifmmode×\else\texttimes\fi1010 dyn cm^\ensuremath-2) have enabled us to accurately study the behavior of the \ensuremathΓ_25^\ensuremath' valence-band maxima and the \ensuremathΔ1 conduction-band minima under stress. The stress splitting of the valence bands is produced by (i) the orbital-strain interaction, which is described by two deformation potentials b1 and d1, and (ii) the stress-dependent spin-orbit interaction, described by b2 and d2. We find that b=b1+2b2=\ensuremath-(2.10\ifmmode±\else\textpm\fi0.10) eV, b2=\ensuremath-(0.1\ifmmode±\else\textpm\fi0.15) eV, d=d1+2d2=\ensuremath-(4.85\ifmmode±\else\textpm\fi0.15) eV, and d2=\ensuremath-(0.05\ifmmode±\else\textpm\fi0.25) eV. The same measurements yield a value for the shear deformation potential of the \ensuremathΔ1 conduction-band minimum E2=\ensuremath-(8.6\ifmmode±\else\textpm\fi0.4) eV. The effect of hydrostatic deformation is interpreted in terms of two deformation potentials: E1+a1 (orbital-strain interaction) and a2 (stress-dependent spin-orbit interaction). We obtain E1+a1=+(1.5\ifmmode±\else\textpm\fi0.3) eV and a2=0. The hydrostatic coefficient of the indirect gap obtained from E1+a1 agrees with hydrostatic pressure measurements. In addition the stress-induced coupling between \ensuremathΔ1 minima and the neighboring \ensuremathΔ_2^\ensuremath' conduction band, described by the deformation potential |E2*|=(8\ifmmode±\else\textpm\fi3) eV, has been observed. Interpretation of the stress dependence of the intensities on the basis of one (\ensuremathΓ15,c or \ensuremathΔ5,v) or two (\ensuremathΓ15,c and \ensuremathΔ5,v) intermediate states gives the first conclusive evidence of a contribution of \ensuremathΔ5,v\ensuremath→\ensuremathΔ1,c virtual transitions to the indirect adsorption edge of this material.