Interface roughness mediated optical decay and carrier dynamics in type II AlAs/GaAs heterostructures

Roughness at the interface between the well and barrier materials in quantum well systems has long been known to be an important factor determining carrier mobility in short period wells. Interface roughness (IR) has also been suggested as a possible decay mechanism in type II AlAs/GaAs heterostructures. Photoluminescence (PL) has been the primary tool used to study type II AlAs/GaAs heterostructures, and can be expected to be strongly influenced by interface roughness both through the carriers' mobility and their decay mechanism. Despite this, IR as a decay mechanism has been the subject of little to no analytical study. Additionally, the available models for IR-limited mobility do not scale with the density of scattering sites and do not include the concept of roughness-bound states. Finally, the nature of the lowest energy PL feature in type II AlAs/GaAs has been in dispute for some time. We address these issues by developing analytical expressions for the IR-limited mobility and IR-mediated optical decay in type II AlAs/GaAs systems which account for the spacing of the roughness and the existence of states bound by the roughness. Furthermore, we develop a computer model which incorporates the above mentioned analytical expressions. By comparing the results of our simulation with experimental data, we show that the unique features observed in this system through PL can be accounted for by the presence of interface roughness.U of I OnlyETDs are only available to UIUC Users without author permissio