Impact of excitation energy on hot carrier properties in InGaAs multi-quantum well structure

Hot carrier solar cells aim to overcome the theoretical limit of single-junction photovoltaic devices by suppressing the thermalization of hot carriers and extracting them through energy selective contacts. Designing efficient hot carrier absorbers requires further investigation on hot carrier properties in materials. Although the thermalization of hot carriers is responsible for a large portion of energy loss in solar cells, it is still one of the least understood phenomena in semiconductors. Here, the impact of excitation energy on the properties of photo-generated hot carriers in an InGaAs multi-quantum well (MQW) structure at various lattice temperatures and excitation powers is studied. Photoluminescence (PL) emission of the sample is detected by a hyperspectral luminescence imager, which creates spectrally and spatially resolved PL maps. The thermodynamic properties of hot carriers, such as temperature and quasi-Fermi-level splitting, are carefully determined via applying full PL spectrum fitting, which solves the Fermi-Dirac integral and considers the band-filling effect in the nanostructured material. In addition, the impact of thermalized power density and carrier scattering with longitudinal optical phonons on the spectral linewidth broadening under two excitation energies is studied.

Automated summary

Hot carrier solar cells aim to improve the efficiency of photovoltaic devices by suppressing hot carrier thermalization and extracting them through energy selective contacts. This study investigates the impact of excitation energy on the properties of hot carriers in an InGaAs multi-quantum well structure at different lattice temperatures and excitation powers. The thermodynamic properties of hot carriers are determined through full PL spectrum fitting and consideration of band filling effects.