Electronic, phononic, and magnetic properties of zinc oxide alloys

The II-VI semiconductor ZnO can be grown at relatively low temperatures on inexpensive substrates. ZnO ranks among the best materials for ultraviolet light emitters, gas sensors, surface acoustic wave devices, and transparent contacts.

The optical room-temperature band gap of undoped ZnO of 3.3 eV can be varied in the whole energy range from 3.18 eV up to 4.5 eV by cationic alloying with Cd or Mg, respectively. The well established one-electron pseudopotential band structure theory for describing experimentally observed electronic properties of Zn(Cd,Mg)O with transferable, structural independent Zn, O, Cd, and Mg empirical pseudopotentials will be presented. Furthermore, the idea of possible calculations of phononic bandstructures utilizing the same empirical pseudopotentials obtained for the electronic bandstructure calculations will be discussed.

At room temperature ferromagnetic ZnO possesses great importance for potential applications in spintronic devices, as for example Spin-LEDs and Spin-FETs. For such spintronic applications ZnO is alloyed with 3d transition metals thus obtaining a diluted magnetic semiconductor (DMS). However, the nature of ferromagnetism in ZnO-based DMS is still under active debate. The successes and shortcomings of the theoretical models describing magnetic phenomena in DMS materials will be listed.