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Structural, Optical, and Magnetic Behavior of in-situ Doped, MOCVD-Grown Ga1-xMnxN Epilayers and Heterostructures

Published online by Cambridge University Press:  01 February 2011

Nola Li ,
William E. Fenwick ,
Martin Strassburg ,
Ali Asghar ,
Shalini Gupta ,
Hun Kang ,
Nola Li ,
Christopher Summers  and
Ian T. Ferguson
Nola Li
Affiliation:
[email protected], Georgia Institue of Technology, Electrical Engineering, 350027 Georgia Tech Station, Atlanta, Ga, 30332, United States, 404-385-2888, 404-385-2886
William E. Fenwick
Affiliation:
[email protected], Georgia Institute of Technology, Electrical and Computer Engineering, United States
Martin Strassburg
Affiliation:
[email protected], Georgia Institute of Technology, Electrical and Computer Engineering, United States
Ali Asghar
Affiliation:
[email protected], Georgia Institute of Technology, Electrical and Computer Engineering
Shalini Gupta
Affiliation:
[email protected], Georgia Institute of Technology, Electrical and Computer Engineering, United States
Hun Kang
Affiliation:
[email protected], Georgia Institute of Technology, Electrical and Computer Engineering, United States
Nola Li
Affiliation:
[email protected], Georgia Institute of Technology, Electrical and Computer Engineering
Christopher Summers
Affiliation:
[email protected], Georgia Institute of Technology, Materials Science and Engineering
Ian T. Ferguson
Affiliation:
[email protected], Georgia Institute of Technology, Electrical and Computer Engineering, United States
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Abstract

Dilute magnetic semiconductors (DMS) show promise as materials that can exhibit ferromagnetism at room temperature (RT). However, the nature of ferromagnetism in this material system must be well understood in order to allow intelligent design of RT spintronic devices. This work investigates the magnetic properties of the as-grown films and the effect of Mn incorporation on crystal integrity and device performance. Ga1-xMnxN films were grown by MOCVD on c-plane sapphire substrates with varying thickness and Mn concentration. Homogenous Mn incorporation throughout the films was verified with Secondary Ion Mass

Spectroscopy (SIMS), and no macroscopic second phases (MnxNy) were detected using X-ray diffraction (XRD). Superior crystalline quality in the MOCVD-grown films relative to Mn-implanted GaN epilayers was confirmed via Raman spectroscopy. Vibrating sample magnetometry measurements showed an apparent room temperature ferromagnetic hysteresis in the as-grown epiayers. Similarly, a marked decrease in the magnetization was observed with annealing and silicon doping, as well as in post-growth annealed Mg-codoped samples. The observed decrease in muB per Mn with increasing Mn concentration is explained by Raman spectroscopy results, which show a decrease in long-range lattice ordering and an increase in nitrogen vacancy concentration with increasing Mn concentration. Magnetic and electron-spin paramagnetic resonance (EPR) data also show that the position of the Fermi level relative to the Mn2+/3+ level is the determining factor in magnetization. Light emitting diodes (LEDs) containing a Mn-doped active region have also been produced. Devices were fabricated with different Mn-doped active layer thicknesses, and I-V characteristics show that the devices become more resistive as thickness of the Mn-doped active layer increases. The magnetic and structural properties observed in this work will be used in conjunction with characteristics and magneto-optical of the Mn-containing devices to discuss the theoretical models of ferromagnetism in Ga1-xMnxN

Keywords

spintronicsemiconductingmagnetic properties
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 892 , 2005 , 0892-FF07-04-EE05-04
Copyright
Copyright © Materials Research Society 2006

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References

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