A proposal for a high-speed In0.52Al0.48As/In0.53Ga0.47As MODFET with an (InAs)m(GaAs)msuperlattice channel

In this letter we examine theoretically the potential of an In0.52Al0.48As/In0.53Ga0.47As modulation-doped field-effect transistor in which the usual InGaAs channel is replaced by an (InAs)m(GaAs)msuperlattice with m ≲ 4, extending over 100 ∼ 200 Å from the InAlAs interface. For small m the superlattice bandstructure is essentially the same as that of the alloy and the effects of the very small lattice mismatch are negligible. More importantly, the electrons in the active channel are not expected to suffer any alloy scattering since the channel now has perfect long-range order with no random potential fluctuations. We show that this MODFET has extremely high mobility and its low-temperature mobility can be an order of magnitude higher than that of the conventional InAlAs/InGaAs MODFET. Comparison is also made with the AlGaAs/GaAs MODFET and results indicate that the proposed structure has superior potential performance.