Optically Induced Degradation Due to Thermally Activated Diffusion in GaN-Based InGaN/GaN MQW Solar Cells

We extensively investigate the degradation of gallium nitride (GaN)-based high periodicity indium GaN (InGaN)-GaN multiple quantum well (MQW) solar cells submitted to optical stress at high excitation intensity and high temperature. The original results reported in this article indicate the presence of a thermally activated diffusion of impurities from the ${p}$ -side of the devices toward the active region (AR), which favors the increase in the Shockley–Read–Hall (SRH) recombination within the MQWs. Appropriate fitting of the degradation kinetics according to Fick’s second law allowed the extrapolation of the diffusion coefficient of the defect involved in the degradation and of the related activation energy. The obtained values suggest that degradation originates from the diffusion of hydrogen. The proposed analytical methodology and the related results provide insight on MQW solar cells degradation and can be used to increase cell performance and reliability in novel applications and harsh environments.