tailieunhanh - Báo cáo hóa học: " Micro-photoluminescence of GaAs/AlGaAs triple concentric quantum rings"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Micro-photoluminescence of GaAs/AlGaAs triple concentric quantum rings | Abbarchi et al. Nanoscale Research Letters 2011 6 569 http content 6 1 569 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Micro-photoluminescence of GaAs AlGaAs triple concentric quantum rings 1 1 22 1 1 Marco Abbarchi Lucia Cavigli Claudio Somaschini Sergio Bietti Massimo Gurioli Anna Vinattieri and Stefano Sanguinetti2 Abstract A systematic optical study including micro ensemble and time resolved photoluminescence of GaAs AlGaAs triple concentric quantum rings self-assembled via droplet epitaxy is presented. Clear emission from localized states belonging to the ring structures is reported. The triple rings show a fast decay dynamics around 40 ps which is expected to be useful for ultrafast optical switching applications. Self-assembled semiconductor quantum nanostructures are currently deeply investigated because of their potentiality as building block for novel quantum optical and optoelectronic devices 1-4 . Several promising applications in these fields such as single photon source for quantum cryptography 1 quantum bits 4 or quantum logical elements 3 4 require the coherent manipulation of the carrier population in the adjacent quantum nanostructures. Within this scenario quantum rings have several interesting peculiarities. First unlike quantum dots the quantum ring ground state total angular momentum changes from zero to non zero by increasing the magnetic field 5 6 . This also results in a peculiar energy dispersion of the excitons for different ring radius. Second since charge tunneling between states of different angular momentum is strongly suppressed by selection rules double concentric quantum rings eventually offer the control of effective coupling of direct-indirect excitons 7 . The possibilities to control the coupling between different rings is indeed of the utmost relevance in the research of semiconductor-based quantum computational devices. The recent success in self-assembly of single and