Growth by molecular-beam epitaxy and characterization of (InAs)m(GaAs)m short period superlattices on InP substrates

Abstract

(InAs)m(GaAs)m short period superlattices (SPSs) have been grown by molecular-beam epitaxy on InP substrates with their layer index m value systematically changed from 1 to 3. Their structural and electrical property dependencies on the layer index m value have been examined. During the first growth stage for the SPSs, with layer index m values of 2 and 3, two-dimensional reflection high-electron energy diffraction growth patterns were observed. The intended periodic structures without misfit dislocation generation were confirmed by x-ray diffraction and transmission electron microscopy (TEM) measurements. However, the obtained electrical properties were still poor, indicating the existence of a large amount of disorder in the SPSs. On the other hand, though the thickness of consisting binary compounds was as thin as one monolayer, a high-quality (InAs)1(GaAs)1 SPS was obtained. The highly ordered monolayer arrangement for InAs and GaAs was first observed by a TEM lattice image as well as x-ray diffraction measurement. The obtained electron Hall mobilities for the modulation-doped N-AlInAs/(InAs)1(GaAs)1 SPS structure were as high as 11 000 cm2/V s at room temperature and 74 000 cm2/V s at 25 K.