科研之友
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摘要
Mn ions were implanted into GaN thin films with six doses ranging from 10(14) to 5 x 10(16) cm(-2) and the samples were subsequently annealed isochronically in three steps at 800, 850 and 900 degrees C. Structural, optical and magnetic properties of the implanted samples were studied after each annealing. X-ray diffraction measurements exhibited new peaks on the lower angle side of the main GaN peak which are attributed to the implantation induced damage as well as the formation of a GaMnN phase. A dose dependent decrease in the optical band gap and an increase in the Urbach tail were observed from optical transmission measurements. The clear magnetic hysteresis loops were recorded by the magnetometer which revealed the room temperature ferromagnetic ordering in all the implanted samples. Unusual behaviour in the magnetic measurements was observed when saturation magnetic moment decreased in all the samples with an increase in annealing temperature from 850 to 900 degrees C. This is explained by the out-diffusion of Mn atoms from the samples during high temperature annealing. Annealing temperature of 850 degrees C for Mn implanted GaN has been suggested as suitable since the samples annealed at this temperature exhibited maximum M(s) and minimum Urbach energy. Bound magnetic polarons are suggested to be the origin of room temperature ferromagnetic exchange in the samples. XPS measurements indicated that the Mn ions have been incorporated into the wurtzite structure of the host lattice by substituting the Ga sites.
- 出版日期2009-7-7
- 单位北京大学
