Magnetic properties of Gd-doped GaN

• Published in: Physica Status Solidi. B: Basic Solid State Physics 2014-09, Vol.251 (9), p.1673-1684
• Main Authors: Shvarkov, Stepan, Ludwig, Astrid, Wieck, Andreas Dirk, Cordier, Yvon, Ney, Andreas, Hardtdegen, Hilde, Haab, Anna, Trampert, Achim, Ranchal, Rocío, Herfort, Jens, Becker, Hans-Werner, Rogalla, Detlef, Reuter, Dirk
• Format: Article
• Language: English
• Subjects: Defects; electrical properties; Ferromagnetism; Gallium nitrides; Hysteresis; Implantation; ion implantation; Magnetic properties; magnetic semiconductors; Magnetization; magnetotransport; Molecular beam epitaxy; treatment conditions
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.201350205

In this paper, we discuss the magnetic properties of Gd‐doped GaN. This diluted magnetic semiconductor shows hysteretic magnetization behavior at room temperature, which is attributed to ferromagnetism with a Curie temperature well above 300 K. However, the experimental results regarding the magnetic properties are not completely consistent and the microscopic origin for the reported magnetic properties is still unclear. We discuss the role of the growth method of the GaN comparing molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) including GaN doped during the growth process with Gd as well as Gd‐implanted material. It seems that in general it is easier to obtain hysteretic magnetization behavior for MBE‐grown material probably due to the higher oxygen and lower hydrogen content. An exception is Gd‐implanted GaN MBE‐grown on Si(111) where we observe no ferromagnetism. We will present experiments where by oxygen implantation and annealing the impurity concentration was manipulated. The role of native defects is addressed and new experiments where additional defects have been introduced by nitrogen implantation in MBE‐grown GaN:Gd are discussed. We present our results on anomalous Hall effect observed in a Gd‐implanted GaN/AlGaN heterostructure. Shvarkov et al. discuss the magnetic properties of Gd‐doped GaN, a diluted magnetic semiconductor showing hysteretic magnetization behavior. However, the experimental results for the magnetic properties are not completely consistent and the microscopic origin of the reported properties is still unclear. The authors discuss the role of the GaN growth method. In general, hysteretic magnetization behavior is obtained for material grown by molecular beam epitaxy (MBE). An exception is Gd‐implanted MBE‐grown GaN on Si(111) where no ferromagnetism is observed. The role of native defects is addressed and new experiments where additional defects have been introduced in MBE‐grown GaN:Gd are discussed. Furthermore, the authors present results on the anomalous Hall effect observed in a Gd‐implanted GaN/AlGaN heterostructure.