Loss Mechanisms in Si Laser Power Converters under High-Injection Conditions

抄録

We performed an inverse analysis of the current–voltage characteristics of Si laser power converters (LPCs) using a drift-diffusion model to clarify the loss mechanisms. The analysis shows that both the electron and hole mobilities decrease monotonically with increasing excitation density, primarily due to enhanced lattice scattering. This mobility degradation induces carrier accumulation in the lightly n-doped absorber, modifies the space-charge density and potential distribution, and consequently degrades the fill factor. Furthermore, by evaluating heat generation, we find that under low-injection conditions, Shockley–Read–Hall recombination and Joule heating account for approximately 36–42% and 43–48% of the total heat generation, respectively, whereas under high-injection conditions these fractions shift to approximately 56% and 30%. These results identify the dominant loss mechanisms that limit the conversion efficiency of Si LPCs under high-power-density operation.