Effect of structural parameters on transport characteristics of GaInAs/AlInAs two-dimensional electron gases grown by molecular beam epitaxy

Abstract

The effect of structural parameters on the transport characteristics from 15 to 300 K of molecular beam epitaxy grown GaInAs/AlInAs two-dimensional electron gas structures lattice matched to InP is determined. The AlInAs buffer layer thickness was varied from 1000 to 10 000 Å. One sample also incorporated a GaInAs/AlInAs superlattice. The AlInAs spacer layer was varied from 25 to 200 Å. The buffer layer thickness and structure has almost no effect on the mobility or sheet density. Increases in the AlInAs spacer thickness resulted in a monotonically decreasing sheet density and a peak in the mobility at 100 Å. The highest 77 K mobility was 66 700 cm2/V s with ND=1.20×1012 cm-2 in the structure with the 100 Å spacer. The effect of illumination and temperature on the sheet concentration in these structures as well as on "bulk" AlInAs:Si is much smaller than in AlGaAs/GaAs structures or "bulk" AlGaAs, indicating that devices based on this material system will not be characterized by freeze-out and persistent photoconductivity.