Analysis of thermodynamic functions of silicon at high temperatures

It is for the first time that the results of experimental studies of variat ion of the enthalpy and heat capacity of silicon are analyzed within the fr amework of anharmonic expansion of the Debye model with due regard for the temperature dependence of the characteristic Debye temperature theta>(*) ov er bar * (T) in the temperature region above room temperature up to the mel ting point. The calculation results in a wide range of temperatures 300 les s than or equal to T less than or equal to 1400 K are in rather satisfactor y agreement with the experimental temperature dependence of the enthalpy va riation of the material. However, in the vicinity of the melting point of s ilicon T-m = 1690 K, the experimental points lie above the predicted curve. The additional increment of the enthalpy of silicon in the premelting regi on, established for the first time in this study, is interpreted within the framework of the Frenkel thermal activation model.