In situ photoemission study of HgTe Quantum Dots for photodetectors

This research investigates the electronic properties of Mercury Telluride (HgTe) Quantum Dots(QDs), a material of growing interest for infrared optoelectronic applications, particularly as an ac-tive layer in photodetectors. The primary characterization technique used is X-ray PhotoemissionSpectroscopy (XPS), which allows to probe the occupied electronic states of the surface. A first key focus is the effect of cesium (Cs) deposition on the QD surface. Building on prior studies showing that alkali metals can lower the work function of semiconductors and metals, we demonstrate a strong increase in the Cs 3d core level signal after successive depositions, confirming the effectiveness of the progressive deposition process. The second aspect of the study explores the influence of operating temperature, with XPS measurements performed between 25°C and 100°C. The results reveal significant shifts in boththe valence band and core level energies, which directly affect majority carrier populations and,consequently, the electrical behavior of transistors incorporating HgTe QDs