Boron atoms possess a short covalent radius and the flexibility to adopt sp2 hybridization, which favour the formation of diverse two-dimensional allotropes of boron. Several examples of such boron sheets with metallic nature have been reported recently. However, a semiconducting boron crystal with a direct bandgap is rarely reported either in bulk boron crystals or in two-dimensional boron sheets. Here, the boron sheets with a direct bandgap are synthesized on a Ni foil substrate by chemical vapor deposition. The boron sheets with 48 boron atoms per unit cell have a quasicubic structure, and they are semiconducting and have a direct bandgap of around 2.4 eV, which are verified by combining theoretical and experimental investigations. The result greatly expands the known allotropy of the fifth element and opens vast opportunities to design 2D boron sheets with tunable optical, electronic, magnetic and chemical properties.

中文翻译：

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准硼片的实验实现。

硼原子具有短的共价半径和采用sp2杂交的灵活性，这有利于形成多样化的二维二维同素异形体。最近已经报道了这种具有金属性质的硼片的例子。然而，在块状硼晶体或二维硼片中很少报道具有直接带隙的半导体硼晶体。在此，通过化学气相沉积在Ni箔基板上合成具有直接带隙的硼片。每个晶胞具有48个硼原子的硼片具有准立方结构，它们是半导体，具有约2.4 eV的直接带隙，已通过理论和实验研究相结合进行了验证。