Ion implanted GaAs/InGaAs lateral injection ridge QW laser for OEICs: study of operation mechanisms

We have fabricated and characterized lateral current injection (LCI) ridge-waveguide lasers with implanted contacts. Comprehensive optical and electrical measurements have been performed over a wide temperature range (10 K to 300 K) on two sets of lasers with differing ridge widths and active region structures. Several new phenomena unique to the LCI mechanism have been observed and explained, including a positive differential resistance kink at threshold, and an inverse temperature-dependence of quantum efficiency and threshold current at cryogenic values. Electron/hole mobility disparity, local carrier nonpinning above threshold due to photon-assisted carrier diffusion, and intrinsically higher current densities have been experimentally identified as the major factors governing LCI laser characteristics. The results have important implications for optimum LCI laser design and ultimate performance.