Optimization of AlAs/AlGaAs quantum well heterostructures on on-axis and misoriented GaAs (111)B
نویسندگان
چکیده
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 TG> 690 C and low As4 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 defect-free AlAs with pronounced step-flow morphology was further achieved by growth on 2 misoriented GaAs (111)B toward 1⁄20 11 and 1⁄22 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/Vs at sheet carrier densities of 5 10 cm . VC 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4711783]
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