Multi-interface roughness effects on electron mobility in a Ga_0.5In_0.5P/GaAs multisubband coupled quantum well structure

Abstract

We analyse the effect of interface roughness scattering on low temperature electron mobility μ n mediated by intersubband interactions in a multisubband coupled Ga 0.5 In 0.5 P/GaAs quantum well structure. We consider a barrier δ-doped double quantum well system in which the subband electron mobility is limited by the interface roughness scattering μ IR n and ionized impurity scattering μ imp n . We analyse the effect of the intersubband interaction and coupling of subband wavefunctions through the barrier on the intrasubband and intersubband transport scattering rates. We show that the intersubband interaction controls the roughness potential of different interfaces through the dielectric screening matrix. In the case of lowest subband occupancy, the mobility is mainly governed by the interface roughness of the central barrier. Whereas when two subbands are occupied, the interface roughness of the outer barrier predominates due to intersubband effects. The influence of the intersubband interaction also exhibits interesting results on the well width up to which the interface roughness dominates in a double quantum well structure.

Effect of electric field on low temperature multisubband electron mobility in a coupled Ga0.5In0.5P/GaAs quantum well structure

“…Normally in quantum wells having narrow widths, the mobility is dominated by IR scattering. [22][23][24] We show here that in the presence of an electric field the dominance of IR scattering on mobility persists in quantum wells of larger well widths. It will be of interest to compare our results with the experimental results when such are available.…”

“…Therefore the drop in B 00 imp is mainly due to the discontinuity of the inverse dielectric screening function matrix near the transition from the double subband occupancy to single subband occupancy. 22 However, in the case of B 00 IR there is no such cancellation. Hence the occurrence of the weight factor ͑1 − cos ͒ in the integrand almost compensates the change in the dielectric screening matrix resulting a monotonic decrease in B 00 IR .…”

“…We note that normally the mobility is governed by the IR scattering for quantum wells of narrow well widths. [22][23][24] However, it is interesting to obtain the mobility dominated by the IR scattering in a quantum well of larger well widths by applying the electric field. Our analysis of the electron mobility for the coupled GaInP/ GaAs quantum well system can be utilized for a variety of low temperature devices incorporating such double quantum wells.…”

“…The electron transport in such multisubband occupied systems has been shown to be influenced by intersubband interactions. [17][18][19][20][21][22] In a recent paper 22 we studied the effect of intersubband interaction on the subband mobility of a coupled GaInP/GaAs double quantum well structure. We showed that the intersubband interaction not only controls the effect of roughness of different interfaces but also exhibits interesting results on the well width up to which the interface roughness ͑IR͒ dominates in a double quantum well structure.…”

Electric field induced enhancement of multisubband electron mobility in strained GaAs/InGaAs coupled quantum well structures

“…Accordingly the subband energy levels and wave functions change leading to modifications in the occupation of subbands. In a system with more than one occupied subband energy levels, the role of intersubband interaction is vital in determining the subband mobility [4][5][6][7]. The intersubband interaction influences the mobility not only through the additional intersubband scattering rate matrix elements but also through the changes in the dielectric screening occurring in the intrasubband scattering rate matrix element [4][5][6][7].…”