Open AccessPhotoluminescence characterization of wetting layer and carrier dynamics for coupled InGaAs/GaAs surface quantum dot pair structures
Author(s) -
Jianwen Liu,
Qing Yuan,
Baolai Liang,
Qiangu Yan,
Ying Wang,
Chunsheng Wang,
Shufang Wang,
Guangsheng Fu,
Yuriy I. Mazur,
Morgan E. Ware,
Gregory J. Salamo
Publication year - 2020
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.393726
Subject(s) - materials science , wetting layer , quantum dot , photoluminescence , optoelectronics , bilayer , quantum tunnelling , relaxation (psychology) , psychology , social psychology , membrane , biology , genetics
The optical properties are investigated by spectroscopic characterizations for bilayer InGaAs/GaAs quantum dot (QD) structures consisting of a layer of surface quantum dots (SQDs) separated from a layer of buried quantum dots (BQDs) by different GaAs spacers with thicknesses of 7 nm, 10.5 nm and 70 nm. The coupling from the BQDs to SQDs leads to carrier transfer for the two samples with thin spacers, 7 nm and 10.5 nm, in which QD pairs are obtained while not for the 70 nm spacer sample. The carrier tunneling time is measured to be 0.145 ns and 0.275 ns from BQDs to SQD through the 7 nm and 10.5 nm spacers, respectively. A weak emission band can be observed at the wavelength of ∼ 960 nm, while the excitation intensity dependent PL and PLE spectra show that this is from the wetting layer (WL) of the SQDs. This WL is very important for carrier dynamics in bilayer structures of BQDs and SQDs, including for carrier generation, capture, relaxation, tunneling, and recombination. These results provide useful information for understanding the optical properties of InGaAs SQDs and for using such hybrid structures as building blocks for surface sensing devices.