Optical Properties of Rotationally Twinned InP Nanowire Heterostructures

Abstract

We have developed a technique so that both transmission electron microscopy and microphotoluminescence can be performed on the same semiconductor nanowire over a large range of optical power, thus allowing us to directly correlate structural and optical properties of rotationally twinned zinc blende InP nanowires. We have constructed the energy band diagram of the resulting multiquantum well heterostructure and have performed detailed quantum mechanical calculations of the electron and hole wave functions. The excitation power dependent blue-shift of the photoluminescence can be explained in terms of the predicted staggered band alignment of the rotationally twinned zinc blende/wurzite InP heterostructure and of the concomitant diagonal transitions between localized electron and hole states responsible for radiative recombination. The ability of rotational twinning to introduce a heterostructure in a chemically homogeneous nanowire material and alter in a major way its optical properties opens new possibilities for band-structure engineering.

Strain-induced band alignment in wurtzite/zinc-blende InAs heterostructured nanowires

“…It has been demonstrated that other factors, like the effect of ZB and WZ fractions along the axis of the wires [8,12] and spontaneous polarization over the valence band [10,15], play crucial role in determining the optical transitions in such systems. The band bending due to induced space charge by spatially separated electrons and holes, typical in type II quantum well, has also been discussed in the literature [12,16]. In polytype NWs inclusion of stacking fault/twinning in the crystal structure, the twin density and periodicity are shown to be reflected in optical transitions in these systems [8,12,17].…”

Structural and optical properties of high quality zinc-blende/wurtzite GaAs nanowire heterostructures

“…To date, relatively broad spectra have been obtained, which do not elucidate the quantum nature of these structures. 29,30 In this work, we present structural and optical properties of very clean GaAs zinc-blende/wurtzite nanowires heterostructures with different average contents of wurtzite phases exhibiting localized and sharp emission characteristics. Thanks to the use of local spectroscopy and time-resolved techniques such as confocal photoluminescence and cathodoluminescence ͑CL͒, the quantum confined nature of these heterostructures is elucidated.…”

Valence band structure of polytypic zinc-blende/wurtzite GaAs nanowires probed by polarization-dependent photoluminescence

“…Unlike the bulk counterparts, the structure of the NWs can consist of pure phases of zinc-blende or wurtzite, or a mixture of the two phases. [5][6][7][8][9][10][11][12] Three different aspects of the wurtzite crystal structure in materials that in bulk exist only in zinc-blende form have been studied up to date. First, nucleation theories have been developed to investigate the appearance of wurtzite structure as a direction for obtaining pure crystal phases.…”