P/N AND OTHER JUNCTION DIODES

P512.4 First generation (1960) ultrahigh speed switching Si diodes and transistors such as the 1N914 and 2N706 used in the first supercomputer, the Control Data Corporation model 6600 attained their speed by doping with the gold recombination center to a concentration of 10¹⁶cm⁻³ because gold has two very efficient recombination levels (see Fig.381.2) and gold can be diffused into Si quickly at low diffusion temperatures due to its high diffusivity in Si (see Fig.512.2). Suppose that this high-temperature gold diffusivity in Si can be extrapolated to room temperature (300K) using the Arrhenius relationship. (a) What is the gold diffusivity in Si at 300K and (b) what is the time to failure (TTF) because the substitutional gold atoms jump (a diffusion step) to adjacent interstitial sites 5A away and assume that the interstitial gold is not an electronic trap or a recombination center?