DEVELOPMENT OF METHODS TO PRODUCE REFINED BEAMS OF NEUTRAL FREE RADICALS FOR SELECTIVE GROWTH OF METASTABLE CONDENSED PHASES

为了进一步发展使用亚稳凝聚相的量子功能纳米器件，近年来巧妙地利用中性自由基的选择性表面反应进行器件加工已变得不可或缺。在中性自由基物质与良好表征的材料表面之间的化学反应的精确实验研究中遇到的问题是如何将动量控制的中性自由基的顺磁通量纯化束供应到表面上。连续供应更加困难，尽管稳定通量连续束通常比脉冲束更适用于薄膜生长应用。为了克服这一困难，研究者提出了几种实验方法来产生稳定通量的中性自由基（RBNR）细化束。负离子束光去电离（PDINIB）和高能复合束光解离（PDECB）是两种主要的研究方法。 ...更多信息 研究中，首先，我们利用PDECB和PDINIB方法制备的RBNR，通过改进试验表面处理装置，进一步提高了中性自由基的产生速率。在本研究过程中，发现了PDECB源化合物光解的独特单分子反应机制。在PDINIB方法应用于高质量（Al，Ga）N低温外延生长过程中光去离子Cr原子掺杂的研究中，我们发现了Cr原子掺入稀磁半导体生长表面的可能性（Al，Ga，Cr）N在斜向辐照下得到增强。此外，我们成功地应用原子Cr的良好准直的中性束来阐明负责自旋电子学所需的亚稳凝聚相的外延生长的角度选择性表面反应机制。少

In order to further evolve quantum-functional nano-devices using metastable condensed phases, it has become indispensable in recent years to ingeniously utilize selective surface reactions of neutral free radicals for the device processing. The problem encountered in the precise experimental study of a chemical reaction between a neutral free-radical species and a well- characterized material surface is how to supply a sufficient-flux purified beam of the momentum-controlled neutral free radicals onto the surface. The continuous supply is all the more difficult, although steady-flux continuous beams are generally more useful for thin-film growth application than pulsed ones. In order to overcome this difficulty the investigator has proposed several experimental approaches to produce steady-flux refined beams of neutral free radicals (RBNR). Two of these approaches are photo-deionization of negative ion beams (PDINIB) and photo-dissociation of energetic compound beams (PDECB).In this st … More udy, firstly, we achieved further enhancement of the rate of neutral free-radical production by improving a trial surface-processing apparatus utilizing RBNR produced by the PDECB and the PDINIB methods. A unique unimolecular-reaction mechanism for the photo- dissociation of the PDECB source compounds was revealed in the course of this study. Furthermore, we realized production of well-collimated hyperthermal beams of various neutral free-radical species.In an application of the PDINIB method to the doping of photo-deionized Cr atoms during the low-temperature epitaxial growth of high-quality (Al, Ga)N by a PDECB-based approach, we found a possibility that the incorporation of the Cr atoms into the growing surface of the diluted magnetic semiconductor (AI, Ga, Cr)N is enhanced by the oblique irradiation. Moreover, we successfully applied the well-collimated neutral beams of atomic Cr to elucidation of the angular- selective surface-reaction mechanism responsible for the epitaxial growth of the desirable metastable condensed phase for spintronics. Less