Reverse bias light emission from GaAs1-xPx diodes

The reverse bias light emission originating at microplasmas was investigated in GaAs_1-xP_x diodes and compared with the forward bias emission. Both spectra were found to be almost identical and could be explained by the same radiative recombination processes. The presence of the strong electric field in the junction gave rise to the Franz-Keldysh effect manifested by the uniform shift (～3 meV) of the reverse bias emission towards longer wavelengths with the Stark effect broadening the free-exciton emission peak P₁. Measurement of the shift indicated that the electric field responsible for this, though high (～10³ V/cm), was considerably lower than that prevailing in the centre of the junction (～5×10⁵ V/cm). This pointed to recombination and the concomitant radiation occurring at the edge of the depletion region, the high field in the centre of the junction inhibiting the recombination of electron hole pairs.