Gerlach J W, Schumacher P, Mensing M, Rauschenbach S, Cermak I, Rauschenbach B
Leibniz-Institut für Oberflächenmodifizierung (IOM), D-04318 Leipzig, Germany.
Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany.
Rev Sci Instrum. 2017 Jun;88(6):063306. doi: 10.1063/1.4985547.
For the synthesis of high-quality thin films, ion-beam assisted deposition (IBAD) is a frequently used technique providing precise control over several substantial film properties. IBAD typically relies on the use of a broad-beam ion source. Such ion sources suffer from the limitation that they deliver a blend of ions with different ion masses, each of them possessing a certain distribution of kinetic energy. In this paper, a compact experimental setup is presented that enables the separate control of ion mass and ion kinetic energy in the region of hyperthermal energies (few 1 eV - few 100 eV). This ion energy region is of increasing interest not only for ion-assisted film growth but also for the wide field of preparative mass spectrometry. The setup consists of a constricted glow-discharge plasma beam source and a tailor-made, compact quadrupole system equipped with entry and exit ion optics. It is demonstrated that the separation of monoatomic and polyatomic nitrogen ions (N and N) is accomplished. For both ion species, the kinetic energy is shown to be selectable in the region of hyperthermal energies. At the sample position, ion current densities are found to be in the order of 1 μA/cm and the full width at half maximum of the ion beam profile is in the order of 10 mm. Thus, the requirements for homogeneous deposition processes in sufficiently short periods of time are fulfilled. Finally, employing the described setup, for the first time in practice epitaxial GaN films were deposited. This opens up the opportunity to fundamentally study the influence of the simultaneous irradiation with hyperthermal ions on the thin film growth in IBAD processes and to increase the flexibility of the technique.
对于高质量薄膜的合成，离子束辅助沉积（IBAD）是一种常用技术，可对多种重要的薄膜特性进行精确控制。IBAD通常依赖于宽束离子源的使用。此类离子源存在局限性，即它们会产生具有不同离子质量的离子混合束，每个离子都具有一定的动能分布。本文介绍了一种紧凑的实验装置，该装置能够在超热能量区域（几电子伏特至几百电子伏特）分别控制离子质量和离子动能。这个离子能量区域不仅在离子辅助薄膜生长方面，而且在制备质谱的广泛领域中都越来越受到关注。该装置由一个收缩型辉光放电等离子体束源和一个配备入口和出口离子光学器件的特制紧凑型四极系统组成。实验证明，单原子氮离子和多原子氮离子（N和N）能够被分离。对于这两种离子种类，在超热能量区域内都能选择动能。在样品位置，发现离子电流密度约为1 μA/cm²，离子束轮廓的半高宽约为10 mm。因此，满足了在足够短的时间内进行均匀沉积过程的要求。最后，使用所描述的装置，首次在实际中沉积了外延氮化镓薄膜。这为从根本上研究超热离子同时辐照对IBAD过程中薄膜生长的影响以及提高该技术的灵活性提供了机会。
