LASER EXCITATION IN A GaAs ANODE i>43 Calculations of Laser Excitation in a GaAs Anode by Slow Electrons

The laser mechanism in a p-type GaAs slab with no junction and a hole concentration higher than 7 x 1018 cm3 is investigated theoretically for the case that the excited electrons are injected from a gas discharge outside the slab. With such an excitation by slow electrons a lower bound of the current density is calculated from the S c h a w lo w —T o w n e s condition. The losses of diffraction and absorption mechanisms are taken into account. Since the slab can be very thin, minimum current densities with laser action of 10 amp./cm2 are possible. Several absorption and excitation mechanisms are discussed. Their relative importance may be found from the spectrum of the laser light and the depth of the activation zone of the slab.