ELECTROLUMINESCENCE FROM A PSEUDOMORPHIC SI0.8GE0.2 ALLOY

Electroluminescence due to recombination of electrons and holes at the band edges of strained Si(1-x)Ge(x) alloy is reported for the first time. This is demonstrated by comparison of the luminescence energy with the photoconductivity threshold of a p-i-n diode incorporating Si0.8Ge0.2, and with the calculated energy gap for the pseudomorphic alloy. The luminescence is strong at low temperature and persists to 220 K. The high intensity of the no-phonon line relative to the momentum-conserving phonon replica in the spectrum shows the scattering in the random alloy is a practical and effective mechanism for enhancing the recombination probability in this indirect semiconductor.