Electronic and Mechanical Coupling in Bent ZnO Nanowires

Abstract

A red shift of the exciton of ZnO nanowires is efficiently produced by bending strain, as demonstrated by a low-temperature (81 K) cathodoluminescence (CL) study of ZnO nanowires bent into L- or S-shapes. The figure shows a nanowire (Fig. a) with the positions of CL measurements marked. The corresponding CL spectra-revealing a peak shift and broadening in the region of the bend-are shown in Figure b.

Outermost tensile strain dominated exciton emission in bending CdSe nanowires

“…It has been demonstrated that compressive and tensile strains will result in wi dening and narrowing bandgap in CdSe crystal, respectively. The similar conclusion has also been widely demonstrated in other semiconductors [7,[15][16][17][18]21,23,24]. Therefore, an inhomogeneous strain field imposed to CdSe crystal will induce a continuous spatial variation of electronic band structures.…”

“…In the bending region, the strain along the hexagonal axis [0001] varies linearly from compressive inside to tensile outside as ε = x/ρ where −d/2 ≤ x ≤ d/2, ρ is the local curvature radius, and d is the diameter of the nanowire. The maximum bending strains at the outer and inner edges of the curved nanowire are ε = ± d/2ρ [17,20], respectively.…”

“…The elastic strain engineering becomes even more important in semiconducting micro/nano-structures because they possess much higher mechanical toughness and strength compared to their bulk counterparts [13,14]. For example, significant energy redshifts of the near-band-edge (NBE) luminescence in uniaxial strain modulated ZnO [15] and GaAs [16] nanowires, as well as in curved ZnO [17][18][19][20] and CdS [21] micro/nanowires have been observed. It has also been reported that the elastic strain-gradient can effectively modulate the photoexcited carrier and exciton dynamics in MoS 2 atomic membrane [7,22] and ZnO micro/ nanowires [23,24].…”

Exciton Drift in Semiconductors under Uniform Strain Gradients: Application to Bent ZnO Microwires

“…Therefore, our investigation demonstrates that the donor-bound exciton drift induced by the elastic strain gradient is the reason of the overall energetic red-shift in bent ZnO micro/ nanowires observed in all previous works. 17,20,21 …”

Observation of enhanced carrier transport properties of Si ⟨100⟩-oriented whiskers under uniaxial strains

“…For low-dimensional materials, the effect of strain on tuning physical properties becomes enhanced when compared with their bulk counterparts owing to the broader tunable range resulted from the large elasticity when the dimension of a material is scaled down. [7][8][9][10][11][12] For example, the loadable elastic strain of nanomaterials can be approximately reached to their theoretical values, [13][14][15][16][17][18][19][20] which can be increased by 2-3 orders of magnitude higher than their bulk forms. Thus, such a huge difference for the loadable strain between the nanomaterials and their bulk counterparts may bring remarkable changes in physical properties.…”