Abstract :
Anomalous enhancement in photoluminescence (PL) spatial-patterns has been investigated in n-GaAs Corbino disks under a pulsed electric field with the short and open circuitry conditions. Under the open circuit, where we apply a pulsed electric field with the width of 101 ns only to the inner electrode of the Corbino contacts geometry, the PL spatial pattern exhibits several bright filaments directing from the inner electrode to the outer one. From the measurements of the PL spectra, the anomalous enhancement of the PL intensity is found to be caused by the impact ionization process of the exciton bound to neutral donors.
