8 - Quantum Dots of Indium Nitrides with Special Magneto-Optic Properties

Abstract

Functionality of low-dimensional structures of indium nitrides can be significantly modified by substitution doping with atoms of “magnetic” elements, such as Ni or Co. Quantum many-body field theoretical studies of electron energy level structure (ELS), molecular electrostatic potential (MEP), and charge and spin density distributions (CDDs and SDDs, respectively) of small InAsN and InN (QDs) containing Ni or Co atoms show that such systems possess uncompensated spin magnetic moment comparable or larger than that of similar QDs containing Mn or V atoms studied in Chapter 5. At the same time, uncompensated spins in such small indium nitride QDs doped with Ni or Co atoms are localized in the vicinity of Ni or Co atoms, rather than delocalized near In atoms or in the bulk of the QDs, which is typical for “diluted magnetic semiconductor” QDs of Chapter 5. Moreover, only a few of such Ni- and Co- doped QDs develop electron charge deficit regions (holes), signifying that nanostructures and thin films composed of such QDs may have bright prospects in applications. In particular, in magnetic recording devices and spintronics the presence of the significant magnetic moment is mission crucial, while electrons as charge carriers are preferred over holes in many cases. Similar to the case of undoped indium nitrides, in the studied Ni- and Co- doped QDs electron charge is accumulated in the vicinity of nitrogen and nickel atoms inside of the QDs, where Ni atoms not only accumulate electron charge on themselves, but also contribute dramatically to re-distribution of electron charge carried by In atoms toward nitrogen atoms. As a result, the ground state energy of the studied Ni-doped QD systems is about 158 H per Ni atom lower than that of their undoped counterparts of Chapter 6, signifying increased stability of the doped systems.