DISTURBED STATE CONSTITUTIVE MODEL FOR THERMOMECHANICAL BEHAVIOR OF DISLOCATED SILICON WITH IMPURITIES

A constitutive modeling approach, called the disturbed state concept ( DSC), is developed to characterize the mechanical response of silicon with dislocations and oxygen impurity. Factors such as dislocation den sity, temperature, strain rate, and oxygen concentration are included in the model. The parameters for a silicon crystal are calibrated base d on stress-strain data reported by Dillon et al. [J. Appl. Phys. 60, 1784 (1986)] and those for silicon with oxygen impurity based on labor atory stress-strain data reported by Yonenaga et al. [J. Appl. Phys. 5 6, 2346 (1984)]. The predictions from the DSC model are compared with those based on the model proposed by Dillon et al. [J. Appl. Phys. 60, 1784 (1986)] and with laboratory test data by Yonenaga et al. [J. App l. Phys. 56, 2346 (1984)]. The correlation between the DSC predictions and test data is very good. It is believed that the DSC can provide a unified and improved constitutive model, compared to previously avail able models, for the thermomechanical behavior of silicon and other ma terials. (C) 1998 American Institute of Physics. [S0021-8979(98)05123- 8]