Investigation of SiGeSn/GeSn/SiGeSn single quantum well with enhanced well emission

In this work, a SiGeSn/GeSn/SiGeSn single quantum well was grown and characterized. The sample has a thicker GeSn well of 22 nm compared to our previously reported 9-nm well configuration. The thicker well leads to: i) lowered ground energy level in Γ valley offering more bandgap directness; ii) increased carrier density in the well; and iii) improved carrier collection due to increased barrier height. As a result, significantly enhanced emission from the quantum well was observed. The strong photoluminescence signal allows for the estimation of quantum efficiency, which was unattainable in previous studies. Using pumping-power-dependent photoluminescence spectra at 20 K, the peak spontaneous quantum efficiency and external quantum efficiency were measured as 37.9% and 1.45%, respectively.

Wasted photons: Photogeneration yield and charge carrier collection efficiency of hematite photoanodes for photoelectrochemical water splitting

Hematite (α-Fe2O3) is a leading photoanode candidate for photoelectrochemical water splitting. Despite extensive research efforts, the champion hematite photoanodes reported to date have achieved less than half of the maximal...