Zn1−xMgxTe and P:Zn1−xMgxTe (x = 0.06–0.25) bulk crystals grown by travelling Te solution method

Abstract

Zn_1−xMg_xTe crystal is expected to be less harmful, more efficient, and economical as a blue-green LED material. In this study, Zn_1−xMg_xTe and P:Zn_1−xMg_xTe crystals with different x (0.06 ≤ x ≤ 0.25) values were prepared by the travelling Te solution method. The required polycrystalline materials for crystal growth were successfully synthesized by an element direct reaction method. The XPS results demonstrate that the Mg element is present in Zn_1−xMg_xTe polycrystalline as Mg²⁺. The lattice constants of zinc-blende Zn_1−xMg_xTe are approximately linearly dependent fitted as α(x) = 6.107 + 0.18x (Å). The Mg content dynamic equilibrium between the source materials, Te solution and crystal was anticipated to be progressively achieved throughout the crystal growth and then the segregation of the Mg in the as-grown crystal is reduced. The ranges of fluctuations in the Mg contents for Zn_0.90Mg_0.10Te and Zn_0.75Mg_0.25Te were 0.092–0.104 and 0.212–0.227, respectively, along the radial direction. When compared to the calculated values found in the literature, there is less axial segregation of the Mg component during the crystal growth. The Mg content along the axial direction of the crystal of Zn_0.82Mg_0.18Te increases at a rate of around 0.0047 cm⁻¹, which is significantly less than that of Zn_0.80Mg_0.20Te crystal grown by the melting method (0.028 cm⁻¹). As-grown Zn_0.90Mg_0.10Te and Zn_0.75Mg_0.25Te crystals have infrared and UV-vis-NIR transmittance values close to 60%, and their bandgaps are between 2.2 eV and 2.4 eV, respectively. The resistivity of intrinsic Zn_0.75Mg_0.25Te crystals is as high as 1.62 × 10⁸ Ω cm. The lowest resistivity of P:Zn_0.92Mg_0.08Te crystals with p-type conduction is 28.6 Ω cm, and the greatest hole concentration is 8.02 × 10¹⁶ cm⁻³, according to the results of the Hall test.