Effect of Substrate Variation on Electrical and Magnetic Properties of Mn Doped ZnO of Dilute Magnetic Semiconductors
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Effect of Substrate Variation on Electrical and Magnetic Properties of Mn Doped ZnO of Dilute Magnetic Semiconductors Srikanth Manchiraju, Govind Mundada, Ted Kehl, Craig vera, Rishi Patel, Pawan Kahol, Kartik Ghosh Department of Physics, Astronomy and Materials Science, Missouri State University , Springfield, MO ABSTRACT
In this paper, the effect of substrate on the domain structure growth and electrical and magnetic properties of epitaxial Mn-doped Zn0.8Mn0.15O (ZnMnO) thin films has been investigated. Epitaxial thin films of ZnMnO dilute magnetic semiconductors (DMS) were grown on various substrates such as single crystal sapphire, single crystal silicon, and quartz substrates using Pulsed Laser Deposition (PLD) technique1. Structural, surface, magnetic, and optical properties have been observed on these films using X-Ray diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and Raman spectroscopy. X-Ray Diffraction shows that films are highly epitaxial and c-axis oriented with some induced strain. AFM images show that film surface is smooth with RMS roughness of the order of 1-2 nm over 5*5sq.micron. Magnetic characteristic properties such as carrier concentration, mobility, and temperature dependent resistivity were also investigated. Carrier concentration decreases and mobility increases for both the films on silicon and quartz substrates when compared to film on sapphire.
INTRODUCTION
DMS are semiconductors which a portion of their constituent ions are replaced by magnetic ions. Semiconductors can be made magnetic by including transition metal atoms into the semiconductor matrix. To incorporate electronics, magnetism, and photonics for multifunctional devices, it is important to find a magnetic semiconductor that not only is ferromagnetic at high temperatures, but which also has tunable carrier density, large mobility, high magnetic moment, and optically transparent in order to be used in devices for spin injection and detection2. These types of materials have a lattice structure similar to that of the undoped semiconductor, at least for the dilute magnetic case. Potential applications of DMS are in the field of spin-dependent semiconductor electronics and optoelectronics, or the so-called spintronics and optospintronics such as spin valves. ZnO and TiO2 doped with Mn and Co have been studied over a time because of interesting magnetic behavior despite the fact that the origin of magnetic behavior is not clearly understood. Most of the theoretical models that have been proposed to explain the ferromagnetism in these materials assume Mn ions as the magnetic impurities3. Oxide diluted magnetic semiconductors have attracted a great interest due to possibility of inducing room temperature ferromagnetism. A theoretical prediction by Dietl et al4 express that the Curie temperature can be increased above room temperature in p-type semiconductor based DMS. Furthermore calculations also show that ferromagnetism is constant in a DMS which is based on a wide band gap s
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