MBE growth and characterization of Sn1-xEu xTe

Abstract

Epilayers of Sn1−xEuxTe (0 < x < 0.03) were grown by molecular beam epitaxy on freshly cleaved BaF 2 (111) substrates and their structural, electrical and optical properties were investigated. The thicknesses of epilayers were about 1.5 µm and deposition was carried out at growth temperatures of 300 o C. The structural properties were investigated by high resolution X-ray diffraction and a sharp film degradation could be observed with increasing europium content. Electrical measurements with temperature varying from 300 to 10K indicated that the epilayers present carrier concentration ranging between 3 × 10 20 and 6 × 10 20 cmand a low resistivity from 6.3 × 10 −5 to 1.2 × 10 −4Ω.cm. From optical measurements it could be seen that spectra present a low energy edge corresponding to the beginning of intra band excitations and the high energy edge due to inter band excitations.

Lead‐Free Thermoelectrics: High Figure of Merit in p‐type AgSnmSbTem+2

“…The patterns can be indexed in the cubic NaCl‐type structure, space group Fm‐3m , with no indication of the existence of a second phase. The calculated lattice parameter, a , of AgSn m SbTe m+2 increases with increasing m value consistent with the difference between the lattice parameter of SnTe (6.30 Å)15 and AgSbTe 2 (6.08 Å)16 (see Figure 1b). The melting points of the AgSn m SbTe m+2 samples determined by differential thermal analysis (DTA) are high, >1000 K (see Figure ).…”

“…Given that, in the related material, TEM of Ag 0.85 SnSb 1. 15 Te 3 revealed extensive nanostructuring, [18] it is not unreasonable to anticipate similar behavior in AgSn m SbTe m+2 . Such an investigation goes beyond the scope of the present study and will be reported in the future.…”

Electrical and thermoelectrical properties of SnTe-based films and superlattices

“…8,9 There are some reports on the SnEuTe ternally alloy and EuTe/SnTe SL. [10][11][12] However, reduction in the carrier concentration has never been reported for this system. Thus, it is considered that the insertion of Eu strongly reduced the number of Sn vacancies in the SnTe layer, leading to the reduction in hole concentration and a drastic increase in hole mobility.…”

Exchange bias in Fe/EuTe(111) bilayers

“…For the preparation of the EuTe films, two individual cells were used as Eu and Te 2 beam source and the growth rate was kept constant at ϳ1.3 Å / s. The EuTe͑111͒ epitaxial layers were grown at 175°C. The growth conditions have to be precisely controlled in order to obtain high quality and smooth EuTe epitaxial films grown in a two-dimensional layer-by-layer mode, 25 since the EuTe͑111͒ surface has a very strong tendency to a three-dimensional growth mode. 26 After the EuTe growth, the samples were transferred to a second MBE system and the Fe and the protective Cu layers were grown at room temperature.…”