Optimization of photoelectric parameters of InGaAs metamorphic laser (λ=1064 nm) power converters with over 50% efficiency

Laser power converters (LPCs) based on InxGa1-xAs/GaAs metamorphic heterostructure grown by MOVPE have been investigated. Both direct study of transmission electron microscopy images and analysis of the dark I-V curves at a low photogenerated current have shown the absence of the effect of threading dislocations from the metamorphic buffer on the LPC parameters. It has been shown, according to the "voltage" and "current" invariants that voltage loss in all investigated LPCs evidences the good quality of p-n junctions for the operating mode of high power laser radiation conversion. It has been also demonstrated that the method of saturation current approximation with current invariant allows obtaining the limit voltage losses irrespective of photogenerated current. Band-gap and thickness of the InGaAs LPCs have been adjusted using spectral characteristics. Fundamental losses (thermal and resistive) and ways to minimize them have been discussed. As a result, LPCs based on In0.23Ga0.77As have demonstrated the laser conversion efficiency (lambda = 1064 nm) of more than 50% with maintaining the efficiency of more than 48% up to 13 W/cm(2).