Modeling of low-temperature specific heat data for Ge27As13S60 and As40S60 glasses by means of the phenomenologically modified soft potential model

Experimental results for the low-temperature specific heat C_p of Ge₂₇As₁₃S₆₀ and As₄₀S₆₀ glasses, measured from 70 K down to 0.54 K, are presented. A maximum in the temperature dependence of the scaled specific heat C_p/T³, appearing in the Boson peak range 2-10 K, and a minimum of this quantity in the tunneling-state range below 1 K, typical for all the glassy materials, were obtained. The presented C_p data are modeled in the frames of a phenomenologically modified soft potential model, applicable in wide low-temperature range. The character of the low-energy excitations in the investigated Ge-As chalkogenides is clarified.     

Low-temperature liquid-phase epitaxy growth from Ga–As–Bi solution

Measurements of Ga–As–Bi liquidus composition at 600 °C for Ga–Bi–GaAs range are reported. High quality GaAs layers and Al_0.28Ga_0.72As/GaAs single quantum well (SQW) structures with different well thicknesses are grown from a mixed Ga + Bi solvent by low-temperature liquid-phase epitaxy method. They are characterized by the Hall effect and photoluminescence (PL) measurements. Significant changes in the layer electrical properties are observed with varying the Bi content in the solution. The layers grown from a mixed solution with 20–30% Bi content are n-type with carrier concentration of 10¹⁴ cm^− 3 and mobility of 40 000 cm²/Vs at 77 K, while p-type high resistivity layers are obtained from a solution with more than 70% Bi content. PL spectra of the SQW structures grown from Ga + 25% Bi solution at 2 K show that the roughness at the interface is less than two monolayers.