Title :
Transient Absorption Spectroscopic Study on Band-Structure-Type Change in CdTe/CdS Core-Shell Quantum Dots
Author :
Wang, Lei ; Wang, Hai-Yu ; Gao, Bing-Rong ; Pan, Ling-Yun ; Jiang, Ying ; Chen, Qi-Dai ; Han, Wei ; Sun, Hong-Bo
Author_Institution :
State Key Lab. for Integrated Optoelectron., Jilin Univ., Changchun, China
Abstract :
We report on the band edge alignment in zinc-blended-type CdTe/CdS core-shell quantum dots, using femtosecond spectroscopy. Time-resolved transient absorption spectroscopy directly shows that the system gradually developed from quasi-type-I to type-II as the shell thickness increased. Following photoexcitation of CdS, the injection of a hole from CdS valence band into CdTe valence band is observed. The hole transfer occurs on the 1000 fs time scale in these heteromaterials. Furthermore, a strain ca. 150 meV is obtained by comparing the transient with steady-state spectra.
Keywords :
II-VI semiconductors; photoexcitation; semiconductor quantum dots; spectroscopy; valence bands; CdTe-CdS; band edge alignment; band-structure-type change; core-shell quantum dots; femtosecond spectroscopy; hole transfer; photoexcitation; steady-state spectra; time-resolved transient absorption spectroscopy; valence band; Absorption; Bleaching; Materials; Photonic band gap; Steady-state; Strain; Transient analysis; Band structure; core-shell quantum dots; strain; transient absorption;
Journal_Title :
Quantum Electronics, IEEE Journal of
DOI :
10.1109/JQE.2011.2159853
