Optimization of AlAs/AlGaAs quantum well heterostructures on on-axis and misoriented GaAs (111)B

F. Herzog, M. Bichler, G. Koblmüller, S. Prabhu-Gaunkar, W. Zhou, M. Grayson
2012 Applied Physics Letters  
We report systematic growth optimization of high Al-content AlGaAs, AlAs, and associated modulation-doped quantum well (QW) heterostructures on on-axis and misoriented GaAs (111)B by molecular beam epitaxy. Growth temperatures T G > 690 C and low As 4 fluxes close to group III-rich growth significantly suppress twin defects in high-Al content AlGaAs on on-axis GaAs (111)B, as quantified by atomic force and transmission electron microscopy as well as x-ray diffraction. Mirror-smooth and
more » ... smooth and defect-free AlAs with pronounced step-flow morphology was further achieved by growth on 2 misoriented GaAs (111)B toward ½0 11 and ½2 1 1 orientations. Successful fabrication of modulation-doped AlAs QW structures on these misoriented substrates yielded record electron mobilities (at 1.15 K) in excess of 13 000 cm 2 /Vs at sheet carrier densities of 5 Â 10 11 cm À2 . V C 2012 American Institute of Physics. [http://dx.
doi:10.1063/1.4711783 fatcat:ueyaz65poffengs73lvunzp7jy