Development of Methods to Generate Refined Beams of Neutral Free Radicals for Control of Surface Fundamental Processes

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用于器件加工已经变得不可或缺。在中性自由基物质与表征良好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通量纯化束提供到表面上。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。 关于我们 首先，我们利用PDINIB法生产的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。RBNR通量的测定是基于我们先前研究中开发的通过光强度调制（ICD）的离子电流差测量进行的。然后，我们将ICD测量系统的S/N比和空间分辨率分别提高了40倍和25倍。在PDINIB方法应用于（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，我们成功地在生产良好的准直中性自由基束，揭示了角度选择性表面反应机制负责外延。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 PDINIB method. The determination of the RBNR flux was performed based on ion-current diference measurement by light intensity modulation (ICD) developed in our previous study. Then, we improved the S/N ratio and the spatial resolution of the ICD measurement system 40 and 25 times, respectively. This improved monitoring system was used for measurements of the spatial profile of the neutral-beam flux.In an application of the PDINIB method to the, doping of photo-deionized Cr atoms during the low-temperature epitaxial growth of (Al, Ga)N by a PDECB-based approach, we found a possibility that incorporation of the Cr atoms into the growing surface of the diluted magnetic semiconductor (Al, Ga, Cr)N is enhanced by the oblique irradiation. Furthermore, we succeeded in production of well-collimated neutral free-radical beams to reveal the angular-selective surface-reaction mechanism responsible for the epitaxy. Less