Strain-induced spatially indirect exciton recombination in zinc-blende/wurtzite CdS heterostructures

Abstract

Strain engineering provides an effective mean of tuning the fundamental properties of semiconductors for electric and optoelectronic applications. Here we report on how the applied strain changes the emission properties of heterostructures consisting of different crystalline phases in the same CdS nanobelts. The strained portion was found to produce an additional emission peak on the low-energy side that was blueshifted with increasing strain. Furthermore, the additional emission peak obeyed the Varshni equation with temperature and exhibited the band-filling effect at high excitation power. This new emission peak may be attributed to spatially indirect exciton recombination between different crystalline phases of CdS. First-principles calculations were performed based on the spatially indirect exciton recombination, and the calculated and experimental results agreed with one another. Strain proved to be capable of enhancing the anti-Stokes emission, suggesting that the efficiency of laser cooling may be improved by strain engineering.

Size-dependent phase transition in methylammonium lead iodide perovskite microplate crystals

“…As the size of the tetragonal inclusions is extremely small, the large blueshift of P 1 emission peak and saturation of P 1 intensity can be observed. This sort of blueshift of emission peaks has been commonly observed in quantum wells and other confined heterostructures 47 48 . Increasing the temperature to 140 K, similar trend was observed except that the blueshift of P 1 becomes negligibly small, which is probably due to the increasing size of tetragonal inclusions.…”

Anomalous photoluminescence enhancement due to hot electron transfer in core–shell Au–CdS nanocrystals

“…5(b)); this observation indicates the origin of narrow lines to be related to intrinsic energy levels of CdS. The present data is in agreement with previous report by Li et al [39], who have found extra emission peak in PL spectra of CdS nanobelts at 77 K due to strain.…”

“…The band gap of ZnO NWs [35] and microwires [36] as well as CdS nanowires/nanotubes [37,38] can be engineered under the influence of strain. In addition to this, strain can also introduce the splitting of exciton emission as demonstrated recently [36,39]. Liao et al [36], report the splitting under the compressive strain while single emission peak is seen under the tensile strain for ZnO microwires.…”

“…Liao et al [36], report the splitting under the compressive strain while single emission peak is seen under the tensile strain for ZnO microwires. In case of CdS nanobelts having both wurtzite and zinc blende crystalline phase [39], additional peak was observed at lower energy region of the band edge emission under the influence of strain and that is blue shifted with increasing strain. In the present work, PL emission of CdS NCs shows the splitting at low temperature which might be due to presence of strain in the sample.…”

Emission energy, exciton dynamics and lasing properties of buckled CdS nanoribbons

“…But as far as we know, the optical tuning ( e.g. PL, exciton’s dynamics and lasing properties) of NRs by strain-engineering has rarely been investigated before 44 45 . In this work, CdS, of which nanostructures have been widely investigated in their optical properties 46 47 48 49 50 51 , is chosen as the test bed because of its high optical quality and very large fracture strength limit 30 .…”