Carriers Transport in Quantum Dot Quantum Well Microstructures of Self-assembled CdTe/CdS/ligand Core-shell System

K. Li
Yanshan University, CN

Keywords: carriers transport, quantum dots quantum well, photovoltaic and photoacoustic effects


The photo-generation carriers’ transport characteristics in CdTe quantum dots (QDs) capped by ligand were probed using a combination of surface photovoltaic (Figure 1) and photoacoustic techniques. The results confirmed that the QDs were composed of the core of CdTe1-xSx nanoparticles and the external surface capped by certain ligand; A quantum dot quantum well (QDQW)’s graded-band-gap structure (Figure 2) and resonance quantum tunneling in the system depended strongly on the properties of the ligands, because the depth of the QWs buried in different interface SCRs was closely related to the molecular conformation of the ligands; If more S atom in -HS group of the ligands participated in forming the CdTe1-xSx layer in between the core-CdTe and the ligands, it might cause an obvious resonance quantum tunneling, prolong the photo-generation carriers’ lifetime at illumination of photonic energy h ≥ Eg, core-CdTe, and decrease the non-radiative de-excitation processes upon illumination especially by the photonic energy h ≤ 2.1 eV. The computer simulation results revealed that the d-frontier orbital in the CdTe super-atom system play a more important role in both the QDQW’s microstructure and resonance tunneling in the system with S-doping in the CdTe cell and the (111) face.