Temperature-accelerated lifetime testing and failure analysis of GaAs and InGaAs laser power converters

Abstract

Laser power converters (LPCs) are key components in laser wireless power transmission systems. In this work, accelerated lifetime tests were conducted on GaAs single-junction and InGaAs single-junction LPCs by elevating the device temperature to 160, 175, and 190 °C to induce accelerated aging. Dark current injections of 8.06 and 8.62 A were applied to GaAs and InGaAs LPCs, respectively, corresponding to simulated photocurrent under laser power densities of 14.65 and 12.78 W/cm2. The failure distributions were fitted using the Arrhenius model, yielding activation energies of 1.11 eV for GaAs single-junction LPCs and 1.15 eV for InGaAs single-junction LPCs. The estimated lifetimes of both devices under an operating temperature of 85 °C are approximately 64 years. Post-aging characterization reveals that device degradation is mainly caused by an increase in series resistance, which leads to a reduction in fill factor and maximum power point. The increase in series resistance is attributed to the degradation of grid electrodes. In addition, the formation of surface cracks is likely associated with the curvature of the LPC exceeding its strain limit.