ABSTRACT
The ‹eld of Spintronics is multidisciplinary in nature; the core concept of this ‹eld is to utilize and control the electron’s charge as well as spin degrees of freedom in the semiconducting system. This emerging ‹eld has led to an extensive search for materials in which semiconducting properties can be integrated with magnetic properties in order to realize the objective of fabrication of spin-based devices [1,2]. The most crucial step to fabricate a practical Spintronics device is the injection of suf‹cient spin-polarized carriers into the semiconducting system. The prediction of magnetic impurity-doped semiconductors (DMSs) can provide an enabling breakthrough in achieving high spin-injection ef‹ciency [3,4]. The 3d transition metal (TM)-doped ZnO can be the most promising dilute magnetic semiconductor (DMS) at room temperature for Spintronics applications [3,5]. Early theoretical studies by Dietl et al. [5] predicted that the TM-doped p-type ZnO might display Curie temperatures above room temperature. In fact, room temperature ferromagnetism has been reported for TM-doped ZnO system, although these materials were n-type [6-9]. However, there exist controversies whether the observed ferromagnetism is intrinsic property of the DMS thin ‹lms or it arises from the clustering or impurities [10-12]. In this context, recent reports about the observation of room temperature ferromagnetism in copper-doped ZnO have been taken with great interest by the scienti‹c community. This is mostly because of the fact that the metallic copper (Cu), as well as all possible Cu-based secondary phases,
CONTENTS
12.1 Introduction ........................................................................................................................ 351 12.2 Structural Analysis ............................................................................................................ 352
12.2.1 Raman Scattering Studies ..................................................................................... 352 12.2.2 Local Structure Analysis of Zn1−xCuxO Thin Films .......................................... 355
12.2.2.1 Detection of Cu-Related Secondary Oxides in Zn1−xCuxO System ..... 355 12.2.2.2 Effect of Cu Substitution in ZnO Lattice ............................................. 356
12.3 Optical Properties of Cu-Doped ZnO Thin Films ........................................................ 362 12.3.1 Low-Temperature Photoluminescence of ZnO .................................................. 362 12.3.2 Photoluminescence of Zn1−xCuxO Thin Films ...................................................365
