Isoelectronic Bound Exciton Photoluminescence in Beryllium-Doped Si_0.92Ge_0.08/Si Superlattices at Elevated Pressure
Abstract
Photoluminescence spectra from three different beryllium-doped Si_0.92Ge_0.08/Si superlattices were measured as a function of hydrostatic pressure at 9 K. Two superlattices (50ÅSiGe/100ÅSi and 20ÅSiGe/100ÅSi) were doped in s itu during MBE growth with Be in the middle of their wells, and the third superlattice (50ÅSiGe/100ÅSi) was doped with Be throughout the alloy and Si layers using implantation. Their PL positions were analyzed by accounting for quantum confinem ent and exciton binding. Using a potential-well model, the exciton binding energy is shown to depend on the width of the wells as well as the position of Be in the superlattice. The pressure dependence of the PL energy (0.8 meV/kbar) is similar to that in bulk Si:Be and Si_0.92Ge_0.08:Be epilayers. The PL peaks disappear above ~ 58 kbar. These observations are analyzed in terms of a modified HTL model.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1996
- Bibcode:
- 1996APS..MAR.N2607K