Instabilities in electroluminescent porous silicon diodes

Abstract
The stability of high quantum efficiency, porous silicon (PS) electroluminescent (EL) diodes have been analyzed under pulsed operation. The results show that EL exhausting is due to a charging of the PS network which recovery is thermally activated (Er∼0.4 eV). This suggests a charge trapping mechanism at larger crystallites with low bandgap, inhibiting further injection of carriers. Also, forward current is found to be thermally activated, however, with a distinctly lower activation energy (Ej∼0.1–0.2 eV), possibly related to jumping of carriers over barriers between nearby crystallites. Finally, high current densities may lead to thermal runaway causing permanent damage to the structure.

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