Electron transport in Al_xGa_1−xAs based double quantum well modulation doped field effect transistor structure: effect of non-square potential profile

The importance of non-square quantum well potential profile on the electron mobility µ of coupled double quantum well based modulation doped field effect transistor (MOD-FET) structure is studied. We consider non-square cubic structure potential, V _DS (z) α z ³, where z denotes the position coordinate from the center of the well. The cubic double quantum well (CD-QW) is made of Al_xGa_1−xAs alloy in which both the side barriers are δ-doped with Si. We consider ionized impurity (imp-) and alloy disorder (al-) scatterings for the calculation of µ. We investigate the variation of the structure parameters, such as well width, barrier width, alloy concentration and doping concentration on µ. The nonlinear behavior of µ can be achieved by properly tuning the structure parameters, mostly controlled by imp-scatterings. We show that under suitable structure parameters µ is enhanced in CD-QW as compared to that of a conventional SD-QW structure. Our analysis will help improve the channel conductivity in QW based MOD-FETs. (paper)