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Optical Properties of Wurtzite GaN and ZnO Quantum Dots

Published online by Cambridge University Press:  21 March 2011

Vladimir A. Fonoberov  and
Alexander A. Balandin
Vladimir A. Fonoberov
Affiliation:
Nano-Device Laboratory, Department of Electrical Engineering, University of California-Riverside, Riverside, California 92521, U.S.A.
Alexander A. Balandin
Affiliation:
Nano-Device Laboratory, Department of Electrical Engineering, University of California-Riverside, Riverside, California 92521, U.S.A.
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Abstract

We have investigated exciton states in wurtzite GaN/AlN and ZnO quantum dots. A strong piezoelectric field in GaN/AlN quantum dots is found to tilt conduction and valence bands, thus pushing the electron to the top and the hole to the bottom of the GaN/AlN quantum dot. As a result, the exciton ground state energy in GaN/AlN quantum dots with heights larger than 3 nm exhibits a red shift with respect to bulk GaN energy gap. It is shown that the radiative decay time in GaN/AlN quantum dots is large and increases from 0.3 ns for quantum dots with height 1.5 nm to 1.1×103 ns for the quantum dots with height 4.5 nm. On the contrary, the electron and the hole are not separated in ZnO quantum dots. Moreover, a relatively thick “dead layer” is formed near the surface of ZnO quantum dots. As a result, the radiative decay time in ZnO quantum dots is small and decreases from 73 ps for quantum dots with diameter 1.5 nm to 29 ps for the quantum dots with diameter 6 nm.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 818: Symposium M – Nanoparticles and Nanowire Building Blocks-Synthesis, Processing, Characterization and Theory , 2004 , M8.2.1
Copyright
Copyright © Materials Research Society 2004

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