First-principles studies on tuning the geometrical, electronical, and optical traits of 2D α-GeTe/Sb Van der waals heterostructure

Van der Waals heterostructures (vdWH) provide an effective technique for tailoring the physical properties of two-dimensional (2D) materials offering exciting possibilities for novel electronics and optoelectronic devices. Here we comprehensively studied the geometrical, electronic, and optical properties of alpha-GeTe/Sb vdWH heterostructure and individual monolayers using first -principles calculations. Using coincident site -lattice matching theory we formed seven different stacking patterns of alpha-GeTe/Sb vdWH denoted as type A, B, C, D, E, F, and G. Through stability analysis, we determined that the type -B alpha-GeTe/Sb vdWH is the most stable structure, with the smallest interlayer distance (3.11 & Aring;) and the lowest cohesive and binding energies. This stable type -B alpha-GeTe/Sb vdWH exhibits properties of an indirect band gap semiconductor with a type -II band alignment, which is advantageous for efficient spatial separation of electrons and holes, a critical feature for advanced nanoelectronics devices. The analysis of the dielectric function, absorption coefficient, and refractive indices of type -B alpha-GeTe/Sb vdWH reveals an improved optical response to UV-visible regions when compared to their monolayers. Significantly, the type -B alpha-GeTe/Sb vdWH exhibits a notably high optical absorption (1.5 x 10 6 cm -1 ) in contrast to other 2D heterostructures. These findings offer promising possibilities for the development of optoelectronic devices based on alpha-GeTe/Sb heterostructures.