Higher mobility of charge carriers in InAs/GaAs superlattices through the elimination of InGaAs alloy disorders on GaAs

In this work, we present the Hall electrical properties for molecular beam epitaxy,grown modulation-doped field-effect transistors structures using a short-period superlattices channel of (InAs)(1.1+/-0.1) (GaAs)(n) where the indexes 1.1 and n represent the number of InAs and GaAs monolayers, respectively These properties are compared with those of structures using the alloy in the channel and the variables were the indium content (y=0.08+/-0.01-0.25+/-0.01) and the channel thickness (80-150 Angstrom). The mobility and the free carrier concentration were obtained as a function of the illumination intensity of a light-emitting diode at 77 K. Our results indicate that for indium content around y=0.08+/-0.01, the electrical properties are independent of using short-period superlattices or alloy channels: For an indium content around y=0.25+/-0.01 the electrical properties change significantly for the two structures. For the same carrier concentration (n=2.8x10(12) cm(-2)), we observed for the sample having the short-period superlattices structure mobilities 33% higher than those for the alloy structure. Our conclusion is that the scattering associated with the alloy disorder increases with the indium content and that this deleterious effect can be reduced, replacing the alloy layer with short-period superlattices.