Abstract
The existence of polytypism in semiconductor nanostructures gives rise to the appearance of stacking faults which many times can be treated as quantum wells. In some cases, despite of a careful growth, the polytypism can be hardly avoided. In this work, we perform an ab initio study of zincblende stacking faults in a wurtzite InP system, using the supercell approach and taking the limit of low density of narrow stacking faults regions. Our results confirm the type II band alignment between the phases, producing a reliable qualitative description of the band gap evolution along the growth axis. These results show an spacial asymmetry in the zincblende quantum wells, that is expected due to the fact that the wurtzite stacking sequence (ABAB) is part of the zincblende one (ABCABC), but with an unexpected asymmetry between the valence and the conduction bands. We also present results for the complex dielectric function, clearly showing the influence of the stacking on the homostructure values and surprisingly proving that the correspondent bulk results can be used to reproduce the polytypism even in the limit we considered.
Highlights
The existence of polytypism in semiconductor nanostructures gives rise to the appearance of stacking faults which many times can be treated as quantum wells
We have observed that at the center of the WZ region, the corresponding bulk density of states (DOS) was reproduced at the band gap neighborhood
Our ab initio analysis of a WZ InP system with ZB stacking faults in the limit of low density of narrow ZB regions confirmed the type II band alignment between the phases, what can lead to the control of the exciton lifetime in this kind of sample
Summary
The existence of polytypism in semiconductor nanostructures gives rise to the appearance of stacking faults which many times can be treated as quantum wells. The fine tuning of the growth conditions can give rise to superlattices of the two polytypes or twin planes along the nanowire axis[6,7] Another interesting subject is the study of the influence of the stacking faults on the nanowire properties what opens the possibility of engineering them through a strict structural control[8,9]. To the best of our knowledge, it is the first time that a sample with stacking faults is modeled using the supercell approach This gives rise to a more realistic description of the system than using bulk results[10,11,12]. Remembering that the ZB stacking faults can be hardly avoided when one wants to grow a pure WZ InP nanowire, in our model, the ZB regions are far from each other, simulating a WZ InP sample with low density of narrow ZB layers
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