Crystal Phase Quantum Dots in the Ultrathin Core of GaAs鈥揂lGaAs Core鈥揝hell Nanowires

详细信息    查看全文

• 作者：Bernhard Loitsch ; Julia Winnerl ; Gianluca Grimaldi ; Jakob Wierzbowski ; Daniel Rudolph ; Stefanie Mork枚tter ; Markus D枚blinger ; Gerhard Abstreiter ; Gregor Koblm眉ller ; Jonathan J. Finley
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：November 11, 2015
• 年：2015
• 卷：15
• 期：11
• 页码：7544-7551
• 全文大小：455K
• ISSN：1530-6992

文摘

Semiconductor quantum dots embedded in nanowires (NW-QDs) can be used as efficient sources of nonclassical light with ultrahigh brightness and indistinguishability, needed for photonic quantum information technologies. Although most NW-QDs studied so far focus on heterostructure-type QDs that provide an effective electronic confinement potential using chemically distinct regions with dissimilar electronic structure, homostructure NWs can localize excitons at crystal phase defects in leading to NW-QDs. Here, we optically investigate QD emitters embedded in GaAs鈥揂lGaAs core鈥搒hell NWs, where the excitons are confined in an ultrathin-diameter NW core and localized along the axis of the NW core at wurtzite (WZ)/zincblende (ZB) crystal phase defects. Photoluminescence (PL)-excitation measurements performed on the QD-emission reveal sharp resonances arising from excited electronic states of the axial confinement potential. The QD-like nature of the emissive centers are suggested by the observation of a narrow PL line width, as low as 鈭?00 渭eV, and confirmed by the observation of clear photon antibunching in autocorrelation measurements. Most interestingly, time-resolved PL measurements reveal a very short radiative lifetime <1 ns, indicative of a transition from a type-II to type-I band alignment of the WZ/ZB crystal interface in GaAs due to the strong quantum confinement in the ultrathin NW core.