Heat treatments of gold-doped silicon diodes

Gold-doped p
⁺
-n silicon diodes were subjected to heat treatments in the 700°-850°C range, and changes in the diode recovery time as a function of heat-treat time were noted. The recovery time was observed to increase with heat-treat time in two stages. In the first stage, the recovery time t
r
increases typically by a factor of 30 in several hours of annealing. In the second stage, which covers an additional 120 hours of annealing, the data points are more scattered, ranging from no increase in t
r
to an increase by a factor of 10. Between the two stages t
r
decreases for a brief period. The data for the first stage fit the interpretation that the gold ceases to function as a recombination center when it jumps from a substitutional site to a nearby interstice. Using this interpretation, the time constant for the process is τ=10
^-3
exp (1.36 eV/kT) seconds. The second stage of annealing is tentatively explained by the annealing of another group of recombination centers. These may be due to interactions of the gold dissociation reaction products among themselves or with other impurities.