Charge carrier-controlled misfit dislocations in ZnS thin films

Zinc sulfide (ZnS) is a semiconductor that exhibits photoplasticity, a ductile-to-brittle transition under light illumination that was reported for bulk specimens [1,2,3]. However, the dislocation glide dynamics in ZnS were also observed to be affected by applied electric fields [4]. Recent computational modeling of dislocation core structures and Peierls barrier calculations show that dislocation cores, that are either Zn-rich or S-rich, have positive or negative charges that trap charge carriers, inducing a core reconstruction, therefore changing its Peierls barrier [5]. Specifically, electrons are expected to be trapped by the positively charged Zn-rich edge dislocation cores, ultimately changing its core structure and increasing its Peierls barrier, thus decreasing the mobility of the dislocation. Hence, the ductile-to-brittle transition, observed by light illumination and induced electric field, might also be achieved by n-type doping. Here, we test this hypothesis by examining the impact of n-type (Al) doping on the glide dynamics of dislocations in ZnS thin films grown by molecular beam epitaxy (MBE). The misfit dislocation (MD) segments in ZnS were shown to have anisotropy in their glide velocity on the [110] vs the [-110] line directions [6]. Electron channeling contrast imaging (ECCI) will be used to image and quantify the formation of interface misfit dislocation networks at the ZnS/GaP interface. We will examine the impact of Al (n-type) concentration on the MD network lengths and anisotropy.



[1] T Zhu et al. Switching the fracture toughness of single-crystal ZnS using light irradiation. Appl. Phys. Lett. 12 April 2021; 118 (15): 154103. https://doi.org/10.1063/5.0047306

[2] Y Oshima et al. Extraordinary plasticity of an inorganic semiconductor in darkness.Science360,772-774(2018).DOI:10.1126/science.aar6035

[3] A Nakamura et al. Nano Letters 2021 21 (5), 1962-1967. DOI: 10.1021/acs.nanolett.0c04337

[4] M Li et al. Harnessing dislocation motion using an electric field. Nat. Mater. 22, 958–963 (2023). https://doi.org/10.1038/s41563-023-01572-7

[5] SP Genlik et al. The Origin of Photoplasticity in ZnS. (2024) arXiv preprint arXiv:2406.13044.

[6] AF Montenegro et al. Crystal Growth & Design 2024 24 (14), 6007-6016. DOI: 10.1021/acs.cgd.4c00559