Effect of non-square structure potential on the multisubband electron mobility in double quantum well structure

Abstract

We study the impact of non-square potential well structure on the electron mobility μ of double quantum well (DQW) based field effect transistors carved out of the AlxGa1-xAs alloy. The barriers lying towards the substrate and surface sides of the DQW are delta doped with Si. We consider DQWs having V-shaped (VDQW), parabolic (PDQW), cubic (CDQW) and square (SDQW) potential wells to obtain the low temperature double subband electron mobility μ. We consider ionized impurity (Imp-) and alloy disorder (Al-) scatterings to calculate μ as a function of well width w and surface electron density NS. We show that the changes in the structure potentials influence the interplay of intersubband effects on the scattering mechanisms differently causing μ(VDQW) < μ(PDQW) ≅ μ(CDQW) as a function of w whereas μ(VDQW) < μ(PDQW) < μ(CDQW) as a function of Ns. We show that μ increases not only with increase in the width of the central barrier b but also decrease with the height of the non-square potentials. Our results can be utilized to analyze the effect of non-square quantum well potentials on the channel conductivity of the quantum well modulation doped field effect transistors.