CAJ | 학술논문

利用等离子体增强化学气相沉积技术制备了厚度不同的Ge薄膜,随着样品厚度的减小,样品表现出了室温铁磁性.厚度为12 nm样品经过300?C退火后,由于颗粒细化,颗粒之间的界面增加,界面缺陷增加,样品表现出最大的铁磁性(50 emu/cm3).场冷却和零场冷却曲线测试表明居里温度约为350 K.进行600?C退火后,颗粒团聚,样品的铁磁性最小.当样品厚度进一步减小为6 nm时,沉积态样品表现出铁磁性和顺磁性共存.对6 nm厚的样品进行300?C退火后,样品只具有铁磁性.进行600?C退火后,样品却只具有顺磁性.12 nm和6 nm厚的Ge纳米结构薄膜随退火温度变化表现出不同的磁性规律,我们认为是由于样品的颗粒大小和颗粒分布不同造成的.样品越薄, Si基底与Ge薄膜之间的界面缺陷越明显,界面缺陷以及Ge颗粒之间的界面缺陷为样品提供了未配对电子,未配对电子的铁磁性耦合强度与样品颗粒的分布以及颗粒之间的结合有一定的关系.颗粒之间分散或颗粒之间的融合程度大都将会降低样品的铁磁性.
이용등리자체증강화학기상침적기술제비료후도불동적Ge박막,수착양품후도적감소,양품표현출료실온철자성.후도위12 nm양품경과300?C퇴화후,유우과립세화,과립지간적계면증가,계면결함증가,양품표현출최대적철자성(50 emu/cm3).장냉각화령장냉각곡선측시표명거리온도약위350 K.진행600?C퇴화후,과립단취,양품적철자성최소.당양품후도진일보감소위6 nm시,침적태양품표현출철자성화순자성공존.대6 nm후적양품진행300?C퇴화후,양품지구유철자성.진행600?C퇴화후,양품각지구유순자성.12 nm화6 nm후적Ge납미결구박막수퇴화온도변화표현출불동적자성규률,아문인위시유우양품적과립대소화과립분포불동조성적.양품월박, Si기저여Ge박막지간적계면결함월명현,계면결함이급Ge과립지간적계면결함위양품제공료미배대전자,미배대전자적철자성우합강도여양품과립적분포이급과립지간적결합유일정적관계.과립지간분산혹과립지간적융합정도대도장회강저양품적철자성.
A series of Ge films with varying thickness is prepared by plasma enhanced chemical vapor deposition technology. With the thickness of the sample becoming thinner, the sample shows ferromagnetism. When the 12-nm-thick sample is annealed at 300 ?C, the partile size becomes smaller, and thus the number of interface defects between the particles increases, so the sample gives a largest magnetic signal at room temperature (50 emu/cm3). FC-ZFC measurement shows that Curie temperature is 350 K. For a higher temperature (600 ?C, the coalescence of small Ge particles makes surface area decline, so magnetic signal becomes weak. With the thickness being 6 nm, the paramagnetism and the ferromagnetism coexist in the 6-nm-thick Ge film. When the 6-nm-thick sample is annealed under nitrogen atmosphere at 300 ?C, the sample only shows ferromagnetism. However, annealed at 600 ?C, the sample only presents paramagnetism. With the annealing temperature changing, the 12-nm-thick film and the 6-nm-thick film show different magnetic phenomena. Particle size and particle distribution cause different magnetic phenomena. It is supposed that the Ge nannostructure unpaired electrons are provided mainly by the interface defect between Si matyix and Ge film and the surface defect of Ge particles. The ferromagnetism coupling of the unpaired electrons is related to the distribution of sample particles and the junction among particles. The fusion between particles will reduce the ferromagnetism of the sample.