Electron and hole mobility in modulation doped GaInAs-AlInAs strained layer superlattice

Abstract

Strain dependence of mobility is measured, ranging from -1% (compressive) to +0.6% (tensile) strain, both for electrons and for holes in modulation doped Ga 1− x In x As-Al 1− y In y As SLSs grown on InP substrates. In each SLS Ga 1− x In x As and Al 1− y In y As have the same layer thicknesses and the same strain magnitude with opposite directions. A graded buffer layer, which might cause lattice mismatch induced scattering centers, is avoided. Room temperature electron mobility is found to not be affected by strain but is found to be proportional to electron effective mass to -3 2 power, which indicates the mobility is limited by polar optical phonon scattering, as in an unstrained bulk layer. On the other hand, hole mobility is found to not change under tensile strain for Ga 1− x In x As, but drastically increases according to the increasing compressive strain for Ga 1− x In x As. Temperature dependence for hole mobilities is measured, which reveals that the dominant scattering mechanism for holes changes according to the applied strain. These results are discussed taking into account strain induced changes in hole effective mass.