Growth temperature dependent evolutions of microstructural,optical and magnetic properties of Zn0.75Co0.25O films

• 来源期刊: 中国物理B（英文版）
• 关键词: diluted magnetic semiconductor ZnO photoluminescence magnetic properties
• 年，卷（期）: 2008,（2）
• 页码范围: 690-696
• 页数: 7页
• 语种: 英文

摘要

Zn0.75Co0.25O films are fabricated via reactive electron beam evaporation.The influence of growth temperature on the microstructural,optical and magnetic properties of Zn0.75Co0.25O films is investigated by using x-ray diffraction,selected area electron diffraction,field emission scanning electron microscope,high resolution transmitting electron microscope,photoluminescence (PL),field dependent and temperature dependent DC magnetization,and x-ray photoelectron spectroscopy (XPS).It is shown that Zn0.75Co0.25O films grown at low temperatures (250-350℃) are of single-phase wurtzite structure.Films synthesized at 300 or 350℃ reveal room temperature (RT) ferromagnetism (FM),while superparamagnetism for 250℃ fabricated films is found above 56 K.PL and XPS investigations show favour towards the perspective that the O-vacancy induced spin-split impurity band mechanism is responsible for the formation of RT FM of Zn0.75Co0.25O film,while the superparamagnetism of 250℃ fabricated film is attributed to the small size effect of nanoparticles in Zn0.75Co0.25O film.