Correlated micro-photoluminescence and electron microscopy studies of the same individualheterostructured semiconductor nanowires

Abstract

To correlate optical properties to structural characteristics, we developed a robuststrategy for characterizing the same individual heterostructured semiconductornanowires (NWs) by alternating low temperature micro-photoluminescence (μ-PL), low voltage scanning (transmission) electron microscopy and conventionaltransmission electron microscopy. The NWs used in this work were wurtzite GaAscore with zinc blende GaAsSb axial insert and AlGaAs radial shell grown bymolecular beam epitaxy. The series of experiments demonstrated that high energy(200 kV) electrons are detrimental for the optical properties, whereas medium energy(5–30 kV) electrons do not affect the PL response. Thus, such medium energyelectrons can be used to select NWs for correlated optical–structural studies prior toμ-PL or in NW device processing. The correlation between the three mainμ-PL bands and crystal phases of different compositions, present in this heterostructure,is demonstrated for selected NWs. The positions where a NW fractures duringspecimen preparation can considerably affect the PL spectra of the NW. Theeffects of crystal-phase variations and lattice defects on the optical properties arediscussed. The established strategy can be applied to other nanosized electro-opticalmaterials, and other characterization tools can be incorporated into this routine.