Theoretical Investigations of Half-Metallicity in Cr-Substituted GaN, GaP, GaAs, GaSb Material Systems MUHAMMAD HANEEF, 1 SUNEELA ARIF, 1,3 JEHAN AKBAR, 1 and ATTIYA ABDUL-MALIK 2 1.—Material Modeling Laboratory, Department of Physics, Hazara University, Mansehra, Pakistan. 2.—Department of Biochemistry, Hazara University, Mansehra, Pakistan. 3.—e-mail: suneela.hu@gmail.com Theoretical investigations of half-metallicity of Cr-substituted Ga 0.875 Cr 0.125 M (M = N, P, As, Sb) material systems are presented in this article The spin polarized band structures, electronic densities of states, spin splitting around the Fermi level and crystal field splitting energies of these materials are addressed in their co-relationship with their possible spintronics applications. These materials are found to be half-metallic, that is, metallic in one spin state and insulator in other. Key words: Spintronic, half-metals, DMS, DFT, dilute magnetic alloys INTRODUCTION The discovery of half-metallicity in III–V diluted magnetic semiconductor systems is the biggest accomplishment for the development of spintronic industry. The long-range ferromagnetism of semi- conductors with higher Curie temperature is very important for improving the efficiency of spin-based devices. On theoretical grounds, both the model Hamilto- nian approach and parameter-free calculations within the density functional theory (DFT) are intensively used to investigate dilute magnetic semiconductors (DMS) 1 The most interesting fea- ture of both these theoretical approaches is the study of the exchange interaction mechanism and the magnetism of these compounds at higher tem- perature. 2–7 The successful spin injection by Ohno et al. 8 has paved the way for new possibilities of making these compounds spintronic components. The discovery of ferromagnetism in GaMnAs by Ohno et al. 9 and Munekata et al. 10 have provided grounds for research on diluted magnetic semiconductors. The incorporation of magnetic ions in the preparation of III–V based DMS is a crucial process. 11 There- fore, different techniques have been adopted for incorporating the magnetic elements into the semi- conductor hetrostructures 12 or planner doping. 13 GaAs/AlGaAs are flexible hetro-structure materials for designing novel spin-based electronic and opto- electronic devices. This justifies our study of Cr-doped III–V as a new material system for applications in the spintronic industry. These materials provide a foun- dation for adding new functionalities to state of the art material systems for devices such as light-emitting diodes, photo detectors, lasers, modulators, integrated circuits, and filters. The III-As compounds belong to the common anion III–V semiconductors. Apart from III-nitrides, these compounds have a wide range of energy gap. Under normal conditions, these compounds crystallize in a zincblende struc- ture. Boron Arsenide (BAs) and Aluminum Arsenide (AlAs) are indirect band gap while Gallium Arsenide (GaAs) and Indium Arsenide (InAs) are direct band gap semiconductor materials. The BAs has resem- blance with silicon in terms of their crystal structure and are a good alternative for alloying with AlAs and GaAs as compared to the wider band gap GaN. Due to the stronger covalent character, BAs possess a peculiar behavior compared to other III–V com- pounds. There are only a few reports about the theoretical and experimental work on the structural and electronic properties of these compounds. Similarly, GaAs is another member of this cate- gory due to its direct band gap and having a higher (Received February 26, 2013; accepted April 11, 2014; published online May 22, 2014) Journal of ELECTRONIC MATERIALS, Vol. 43, No. 9, 2014 DOI: 10.1007/s11664-014-3181-7 Ó 2014 TMS 3169