The effect of variations in temperature and in material parameters on the velocity-field characteristic of gallium arsenide

A model for the velocity-field characteristic of gallium arsenide is developed which is based on the assignment of two separate temperature values to the carrier populations of upper and lower conduction-band valleys. The model takes into account two significant factors; (1) the temperature dependence of carrier relaxation time, and (2), the effect of high electric field intensities on the mobility of carriers in the upper conduction-band valley. The resulting characteristic agrees well with those both predicted and observed by other workers whilst the model allows direct insertion of material parameters into the relevant equations. As the ambient temperature increases, a significant reduction in the ratio of peak-to-valley carrier velocity is shown to occur, together with a small increase in the value of the threshold field.