Photogeneration and Performance Optimization (PhPO): A New Algorithm to Improve the Performance of Vertical Epitaxial Hetero-Structure Architecture Laser Power Converters

The state of the art in the field of high-power laser transmission is dominated by the so called Vertical Epitaxial Hetero-Structure Architecture (VEHSA), which consists of monolithically stacking p/n cells connected by tunnel junctions. This configuration distributes the current between the cells and reduces the losses due to Joule heating. Since assessing the performance of each individual cell is very challenging, the design and optimization of these devices relies on simple approximations based on the Beer-Lambert law, the exponential decay of light, and guessing from published data. The limitations of these approaches are i) the current of each cell may differ from the calculated photocurrent, producing a mismatch and limiting the overall current, ii) the design parameters cannot be individually evaluated, and iii) the loss of accuracy when applied to devices with light trapping mechanisms. In this work, we present a novel optimization methodology aimed to overcome these limitations, based on a meticulous device Technology Computer-Aided Design (TCAD) and an iterative optimization algorithm with two stages: Photogeneration and Performance Optimization (PhPO). The proposed procedure improves the performance of the current state-of-the-art VEHSA devices, allows the use of new semiconductors and makes the design more resilient to a wide range of operation conditions.