The downscaling of silicon-based structures and proto-devices has now reached the single-atom scale, representing an important milestone for the development of a silicon-based quantum computer. One especially notable platform for atomic-scale device fabrication is the so-called Si:P δ-layer, consisting of an ultra-dense and sharp layer of dopants within a semiconductor host. Whilst several alternatives exist, it is on the Si:P platform that many quantum proto-devices have been successfully demonstrated. Motivated by this, both calculations and experiments have been dedicated to understanding the electronic structure of the Si:P δ-layer platform. In this work, we use high-resolution angle-resolved photoemission spectroscopy to reveal the structure of the electronic states which exist because of the high dopant density of the Si:P δ-layer. In contrast to published theoretical work, we resolve three distinct bands, the most occupied of which shows a large anisotropy and significant deviation from simple parabolic behaviour. We investigate the possible origins of this fine structure, and conclude that it is primarily a consequence of the dielectric constant being large (ca. double that of bulk Si). Incorporating this factor into tight-binding calculations leads to a major revision of band structure; specifically, the existence of a third band, the separation of the bands, and the departure from purely parabolic behaviour. This new understanding of the band structure has important implications for quantum proto-devices which are built on the Si:P δ-layer platform.

硅基结构和原型设备的缩减规模现已达到单原子级，这代表了硅基量子计算机发展的重要里程碑。为原子级器件的制造的一个特别显着的平台是所谓的Si：P δ i-层，由半导体主机内的超高密度和掺杂剂的尖锐层。尽管存在多种选择，但在Si：P平台上已经成功展示了许多量子原型设备。因此，计算和实验都致力于理解Si：Pδ的电子结构。层平台。在这项工作中，我们使用高分辨率的角度分辨光发射光谱法揭示了由于Si：Pδ的高掺杂密度而存在的电子态的结构。-层。与已发表的理论著作相比，我们解析了三个不同的波段，其中最多的波段表现出较大的各向异性，并且与简单的抛物线行为存在显着偏差。我们研究了这种精细结构的可能起源，并得出结论，这主要是介电常数很大（大约是体硅的两倍）的结果。将这一因素纳入紧束缚计算中，会导致对能带结构的重大修改。具体而言，存在第三条带，条带分离以及偏离纯粹的抛物线行为。这种新的能带结构的理解有哪些是建立在硅量子原器件具有重要意义：P δ -层平台。