Search for content and authors
 

The growth of Cr-doped GaN by MOVPE for spintronics

Yong Suk Cho 1Nicoleta Kaluza 1Nicolas Thilosen 1Vitalyi Guzenko 1Thomas Schaepers 1Hilde Hardtdegen 1Uwe Breuer 2Mohammed Reza Ghadimi 3Marian Fecioru-Morariu 3Bernd Beschoten 3Hans Lueth 1

1. Research Center Juelich, Institute of Bio and Nanosystems (IBN), Leo-Brandt Str., Jülich 52425, Germany
2. Research Center Juelich, Central Division of Analytical Chemistry (ZCH), Leo-Brandt Str., Jülich 52425, Germany
3. II. Physikalisches Institut, RWTH Aachen, Templergraben 55, Aachen 52056, Germany

Abstract

Transition metal doped GaN based diluted magnetic semiconductors are very attractive candidate for future "spintronics" devices based on carrier-induced ferromagnetism. Theoretical calculations predicted that Cr-doped GaN was found to have the most stable ferromagnetic state in transition metal doped GaN. Up to now, Cr-doped GaN layers have been grown only by molecular beam epitaxy. Although metal organic vapor phase epitaxy (MOVPE) is a mature technique regarding the layer quality, no growth of Cr-doped GaN layers by MOVPE has been reported, yet. In this study we investigate the growth of Cr-doped GaN layers by MOVPE and their characterization. Conventional Ga and N precursors were used while bis(cyclopentadienyl)chromium (Cp2Cr) was employed as the Cr precursor. The influence of precursors supply, carrier gas type and growth temperature on Cr incorporation efficiency in the GaN layers will be discussed. Secondary ion mass spectrometry (SIMS) was used to verify the incorporated Cr fraction in the layers. A linear dependence between mole fraction of Cp2Cr in gas phase and incorporated Cr in solid phase was found. So far Cr-doped GaN layers with Cr concentrations in solid phase up to 2 ´ 1019 at/cm-3 were grown. Scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and photoluminescence (PL) measurements were performed to investigate the surface morphology, structural and optical properties of these layers. Superconducting quantum interference device (SQUID) zero field heating measurements showed a remanent magnetization even above room temperature for the Cr-doped GaN layers.

 

Legal notice
  • Legal notice:
 

Related papers

Presentation: Oral at E-MRS Fall Meeting 2006, Symposium E, by Yong Suk Cho
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 13:48
Revised:   2009-06-07 00:44