van der Waals Epitaxial\nGrowth of Centimeter-Scale\nCdTe Thin Films for High-Performance Photodetectors

Group\nII–VI semiconductor CdTe is widely used\nin optoelectronic\ndevices because of its high absorption coefficient and good chemical\nstability. High-quality CdTe thin films serve as the foundation for\nhigh-performance optoelectronic devices. In this work, centimeter-scale\nCdTe thin films were synthesized via van der Waals heteroepitaxy on\nmica substrates using vapor phase transport (VTD), and planar structure\nphotodetectors (PDs) were constructed via depositing the Au electrodes\non the surface directly or exfoliated buried interface. The results\nshow that the performance of PDs constructed using a CdTe buried interface\nis much better than those constructed using a CdTe surface under the\nlight irradiation at the wavelengths of 406, 642, and 808 nm, and\nthe switching ratio can reach up to 2 × 10<sup>4</sup>, with\na response of 4.4 A/W and a short response time of 1.5 ms. The smooth\ninterface morphology and a large area of flat and dense surfaces are\nconducive to carrier transport, showing better performance. Furthermore,\nflexible PDs are constructed via transferring CdTe thin films onto\na poly(ethylene terephthalate) (PET) substrate and exhibit excellent\nflexibility and stability, which can maintain 96.5% original performance\nwith more than 200 times bending at a curvature radius of 5 mm. The\nresearch indicates that the high-quality, centimeter-scale CdTe with\nburied interface fabricated via van der Waals epitaxial growth is\na promising potential candidate in high-performance optoelectronic\ndevices.