ELECTROLUMINESCENCE IN A-SI-H P-I-N JUNCTIONS

Time resolved and steady state electroluminescence (EL) measurements have been performed in a-Si:H p-i-n junctions at 10K < T < 300K. Steady state measurements reveal characteristics of bimolecular recombination at low generation rates. The quantum efficiency of the EL is low (almost-equal-to 3% of the photoluminescence efficiency at 30K). At low temperatures the rise of the EL, following a rectangular forward current pulse, consists of a fast component with a time constant of a few mu-s and a slow component with a time constant of about a ms. The data suggest that at low temperatures the time response of the EL is determined by the recombination but at high temperatures by the time to build up the carrier density for bimolecular radiative recombination. The fast component of the EL is attributed to the field enhanced recombination of carriers which survived from the preceding pulse.