A pronounced anisotropy is observed in the low-temperature mobility of a two-dimensional electron gas formed in an In0.75Ga0.25As/In0.75Al0.75As quantum well grown on a GaAs substrate. We show that the mobility differences along [011] and [01-1] directions are mainly due to In concentration modulations. Spatially resolved photoemission measurements show an asymmetric indium concentration modulation, correlated with the surface morphology observed by atomic force microscopy. A theoretical model considering conduction band energy modulations agrees well with the transport measurements. The identification of this mobility limiting mechanism allowed us to design and grow higher quality two-dimensional electron gas, needed for high indium content InGaAs device fabrication.
Transport anisotropy in InGaAs two-dimensional electron gases induced by indium concentration modulation / D., Ercolani; G., Biasiol; E., Cancellieri; M., Rosini; Jacoboni, Carlo; F., Carillo; S., Heun; L., Sorba; F., Nolting. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 77:(2008), pp. 235307-1-235307-9.
Transport anisotropy in InGaAs two-dimensional electron gases induced by indium concentration modulation
JACOBONI, Carlo;
2008
Abstract
A pronounced anisotropy is observed in the low-temperature mobility of a two-dimensional electron gas formed in an In0.75Ga0.25As/In0.75Al0.75As quantum well grown on a GaAs substrate. We show that the mobility differences along [011] and [01-1] directions are mainly due to In concentration modulations. Spatially resolved photoemission measurements show an asymmetric indium concentration modulation, correlated with the surface morphology observed by atomic force microscopy. A theoretical model considering conduction band energy modulations agrees well with the transport measurements. The identification of this mobility limiting mechanism allowed us to design and grow higher quality two-dimensional electron gas, needed for high indium content InGaAs device fabrication.
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