Investigations Of Lateral Current Injection Lasers: Internal Operating Mechanisms And Doping Profile Engineering

Lateral current injection lasers grown on semi-insulating substrates are natural candidates for monolithic optoelectronic integration. The lateral injection geometry is demonstrated herein to differ qualitatively from the conventional vertical injection paradigm in ways which are physically interesting and technologically important. By considering the physics of ambipolar diffusion in the presence of a position-dependent rate of recombination resulting from non-radiative, spontaneous, and stimulated processes, we predict that shifting the location of dopants relative to the optical mode may significantly improve the output characteristics of the device. Our 2D numerical modeling confirms this expectation, predicting that a factor of 1.5 improvement in the differential quantum efficiency of the device simulated may be obtained by shifting the lateral p-i junction 0.6 mu m toward the centre of the 1.5 mu m ridge. We predict quantitatively and explain physically one reason for pronounced roll-off in the L-I characteristics of devices reported in the literature, and demonstrate that shifting the doping front may reduce this non-linearity dramatically. We conclude as to the need to approach lateral current injection as a qualitatively different problem from conventional vertical injection in order for the tremendous potential of these devices to be realized fully.