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Continuous and Time Resolved Optically Detected Magnetic Resonance Studies of InP Nanoparticles

Published online by Cambridge University Press:  21 March 2011

L. Langof ,
E. Ehrenfreund ,
E. Lifshitz ,
O. I. Micic  and
A. J. Nozik
L. Langof
Affiliation:
Solid State Institute, Technion – Israel Institute of Technology, Haifa 32000, Israel
E. Ehrenfreund
Affiliation:
Solid State Institute, Technion – Israel Institute of Technology, Haifa 32000, Israel
E. Lifshitz
Affiliation:
Solid State Institute, Technion – Israel Institute of Technology, Haifa 32000, Israel
O. I. Micic
Affiliation:
National Renewable Energy Laboratory, Golden, Colorado 80401, USA
A. J. Nozik
Affiliation:
National Renewable Energy Laboratory, Golden, Colorado 80401, USA
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Abstract

Carriers in small colloidal InP nanoparticles are in strong quantum confinement regime. The low temperature photoluminescence spectrum of InP nanoparticles is composed of an excitonic luminescence at high energies and a non-excitonic defect emission band at lower energies. HF etching of the nanoparticles reduces the defect emission and enhances the exciton process.

In this work we apply optically detected magnetic resonance spectroscopy (ODMR) both in continuous wave and time resolved mode (TR-ODMR) to study the defect luminescence in InP nanoparticles. The results show that the defect luminescence originates from weakly coupled electron-hole pair, where the electron is trapped at the surface by phosphorous vacancy, Vp, and the hole is located at the valence band. Additionally, the results suggest that the non-etched samples are dominated by Vp at the surface. Those are mainly eliminated upon HF treatment, leaving behind small percent of Vp in the core of the nanoparticle. We also find the electron-hole exchange interaction from circular polarized ODMR measurements. The TR-ODMR measurement further clarifies the spin dynamics and characteristic of the magnetic sites. Fitting these measurements to the simulated response of the PL intensity to the square wave modulated microwave power revealed that the spin relaxation time and radiative lifetime of electron-hole pair in the nanoparticles are in the microseconds regime.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 692: Symposium H – Progress in Semiconductor Materials for Optoelectronic Applications , 2001 , H9.23.1
Copyright
Copyright © Materials Research Society 2002

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References

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