Thermal Expansion and Gruneisen Parameters of Amorphous Silicon: A Realistic Model Calculation

摘要

Using a realistic model, the mode Gruneisen parameters and the temperaturedependent coefficient of linear thermal expansion are calculated for amorphoussilicon. The resulting values of the Gruneisen parameters differ from thecrystalline case in having all diversity suppressed, except for a minority ofhigh-frequency localized and low-frequency resonance modes. The latter havevery large, mostly negative Gruneisen parameters (up to -31), caused by volumedriven internal strain. As a result, the values for thermal expansivity arelower than those of crystalline silicon and are sample dependent.