Thin films of barium fluorides with different thicknesses were deposited on GaAs substrate by electron beam evaporation. The aim of the work was to identify the best growth conditions for the production of coatings with a low work function suitable for the anode of hybrid thermionic‐photovoltaic (TIPV) devices. The chemical composition and work function φ of the films with different thicknesses were investigated by X‐ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The lowest value of φ = 2.1 eV was obtained for the film with a thickness of ~2 nm. In the valence band spectra of the films at low kinetic energy, near the cutoff, a characteristic peak of negative electron affinity was present. This effect contributed to a further reduction of the film's work function.

中文翻译：

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超薄氟化钡薄膜的功函数和负电子亲和力

通过电子束蒸发在GaAs衬底上沉积不同厚度的氟化钡薄膜。这项工作的目的是确定适用于混合热电子-光伏（TIPV）装置阳极的低功函涂层生产的最佳生长条件。通过X射线光电子能谱（XPS）和紫外光电子能谱（UPS）研究了不同厚度的薄膜的化学组成和功函数φ。φ的最小值对于厚度为〜2nm的膜获得＝ 2.1eV。在低动能下的膜的价带谱中，在截止附近，存在负电子亲和性的特征峰。这种效果进一步降低了胶片的工作功能。