Recombination Radiation from Silicon Under Strong-Field Conditions

In an attempt to determine the distribution in energy of hot electrons and holes in silicon placed in an intense uniform electric field, measurements have been made of the spectral distribution of recombination radiation at 77°K (field strengths up to 3700 v ${\mathrm{cm}}^{-1\mathrm{}}$) and at 20°K. No change in the spectrum with field was observed, other than a rise in temperature of 6° at 77°K due to Joule heating at 3700 v ${\mathrm{cm}}^{-1\mathrm{}}$ in the sample, from which it was concluded that recombination radiation at these temperatures arises predominantly from the decay of excitons formed the hot carriers, and that the excitons have a thermal distribution of energy at the lattice temperature. In addition, results are given for the spectrum of the radiation from avalanche breakdown regions in reverse-biased silicon $p-n$ junctions at 77° and 300°K; no differences were detected in the range of energies 1.0-1.4 ev, from which it was concluded that exciton decay does not contribute to the observed radiation at 77°K.