Photo-enhanced magnetization in semiconductors thin films incorporating magnetic dots

2000年报道了在GaAs（001）衬底上交替淀积Fe和GaAs，在580 ℃的高温下，室温下光照可以增强磁性复合薄膜的磁化强度。虽然这是一个非常令人鼓舞的成就，为未来的应用，如无线微电子机械系统，光增强磁化（PEM）的起源仍然不清楚。部分原因是这些样品由多晶颗粒结构组成，其组成成分没有得到很好的设计和控制。本研究以确定PEM的关键材料和阐明PEM的机理为出发点，系统地研究了Fe_3Ga_As_x和GaAs交替沉积制备的样品<2-x>在不同的沉积顺序和不同的衬底温度下的PEM性能，并研究了T_<s->GaN基复合结构的形成机理。 关于我们 调查。结果表明，以[100-nmGaAs/50-nmFe_3Ga_As_x<2-x>/100-nmGaAs]为堆叠单元，在Ts = 600℃时，用分子束沉积法制备的样品具有显著的PEM效应。通过纳米电子探针分析的冶金学评价表明，变磁性金属Fe_3Ga_4是所观察到的PEM的原因。讨论了该化合物的形成是GaAs与Fe_3Ga_As之间层间扩散过程的结果<2-x>。粒子间相互作用模型的假设，在2000年研究的初始阶段引入。对PEM的功率依赖性的系统研究表明，磁化强度的增加主要是由光致加热主导的，而纯光子激发也可能有助于PEM，正如PEM的幅度超过简单加热所能预期的最大值这一事实所表明的那样。这种新颖的效果应该在未来的工作中继续追求。少

Enhancement of magnetization by the light illumination at room temperature (RT) has been reported in the year 2000 for semiconductor-magnetic composite films prepared by the alternative deposition of Fe and GaAs on GaAs(001) substrates at high substrate temperature of 580 "C. While this was a very encouraging achievement for the future applications such as the wireless micro-electronic mechanical system, the origin of the photo-enhanced magnetization (PEM) has remained unclear. It was partly because of the fact that those samples consisted of polycrystalline, granular structures whose constituent ingredients were not well engineered nor controlled. This research was initiated with the aim to identify the key materials and elucidate the mechanism of PEM.Systematic studies of samples prepared by the alternative deposition of Fe_3Ga_<2-x>As_x and GaAs were carried out with various deposition sequences and different substrate temperatures T_<s-> GaN-based composite structures were also inv … More estigated. It was found that the samples prepared by molecular beam deposition with the stacking the unit of [100-nm GaAs/50-nm Fe_3Ga_<2-x>As_x/100-nm GaAs] at T_s = 600℃ exhibit significant PEM effect. Metallurgical evaluation by nano-electron probe analysis has revealed that metamagnetic metal Fe_3Ga_4 is responsible for the observed PEM. It was discussed that this compound was formed as a consequence of the interlayer diffusion process between GaAs and Fe_3Ga_<2-x>As. The hypothesis of the inter-particle interaction model, which was introduced at the initial stage of the study in 2000. was found not to be the principle mechanism for the observed PEM effect.Systematic studies on power dependence of PEM suggest that the increase of magnetization is primarily dominated by the light-induced heating, whereas pure photonic excitation may also contribute the PEM, as manifested itself by the fact that the magnitude of PEM exceeds beyond the maximum value that can be expected from simple heating. This novel effect should be pursued in the future work. Less