Mg₂Si_xSn_1-xheterostructures on Si(111) substrate for optoelectronics and thermoelectronics

Abstract

Thin (50-90 m) non-doped and doped (by Al atoms) Mg 2 Sn 0.6 Si 0.4 and Mg 2 Sn 0.4 Si 0.6 films with roughness of 1.9-3.7 nm have been grown by multiple deposition and single annealing at 150 o C of multilayers formed by repetition deposition of three-layers (Si-Sn-Mg) on Si(111) p-type wafers with 45 cm resistivity. Transmission electron microscopy has shown that the first forming layer is an epitaxial layer of hex-Mg 2 Sn(300) on Si (111) [110] have been found for the epitaxial layer. But inclusions of cub-Mg 2 Si were also observed inside hex-Mg 2 Sn layer. It was found that the remaining part of the film thickness is in amorphous state and has a layered distribution of major elements: Mg, Sn and Mg without exact chemical composition.It was established by optical spectroscopy data that both type films are semiconductor with undispersed region lower 0.18 eV with n o = 3.59 ± 0.01, but only two direct interband transitions with energies 0.75-0.76 eV and 1.2 eV have been determined. The last interband transition has been confirmed by photoreflectance data at room temperature. Fourier transmittance spectroscopy and Raman spectroscopy data have established the formation of stannide, silicide and ternary compositions.

Design of magnetron co-sputtering configuration for preparing magnesium tin silicide-based thermoelectric alloy thin films

“…In literature, there have been limited works on the MgSiSn thin films, as compared to the bulk form. Typically, a study on the very thin MgSiSn film (50 -90 nm) deposited on Si substrate was reported for optoelectronic and thermoelectric applications 6 . The used deposition technique, however, was a solid phase epitaxy (SPE), which is quite a complicated, expensive and hard-to-control method.…”