Deep levels in ashyphen;grown and Sihyphen;implanted In0.2Ga0.8Asndash;GaAs strainedhyphen;layer superlattice optical guiding structures

摘要

Trap levels in sim;2hyphen;mgr;m In0.2Ga0.8As (94 Aring;)/GaAs(25 Aring;) strainedhyphen;layer superlattices, suitable for optical waveguides, have been identified and characterized by deephyphen;level transient spectroscopy and optical deephyphen;level transient spectroscopy measurements. Several dominant electron and hole traps with concentrations sim;1014cmminus;3, and thermal ionization energies Dgr;ETvarying from 0.20 to 0.75 eV have been detected. Except a 0.20hyphen;eV electron trap, which might be present in the In0.2Ga0.8As well regions, all the other traps have characteristics similar to those identified in molecularhyphen;beam epitaxial GaAs. Of these, a 0.42hyphen;eV hole trap is believed to originate from Cu impurities and the others are probably related to native defects. Upon Si implantation and halogen lamp annealing, new deep centers are created. These are electron traps with Dgr;ET=0.81 eV and hole traps with Dgr;ET=0.46 eV. Traps occurring at room temperature may present limitations for optical devices.