Observation of tunable band gap and anisotropic Dirac semimetal state in black phosphorus
Observation of tunable band gap and anisotropic Dirac semimetal state in black phosphorus
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DOI：
10.1126/science.aaa6486
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发表时间：
2015-08-14
期刊：
影响因子：
56.9
通讯作者：
Kim, Keun Su
中科院分区：
文献类型：
--
作者：
Kim, Jimin;Baik, Seung Su;Kim, Keun Su
黑磷由磷烯的堆叠层组成，磷烯是一种具有前景的器件特性的二维半导体。我们报道了利用原位表面掺杂技术在少层掺钾的黑磷中实现了宽可调的带隙。通过能带结构的测量和计算，我们表明，掺杂剂的垂直电场调制的带隙，由于巨大的斯塔克效应，并调谐材料从一个中等的间隙半导体带反转半金属。在这个带反转的临界场，材料变成具有各向异性色散的狄拉克半金属，在扶手椅上线性，在Z字形方向上二次。黑磷的可调谐能带结构可以允许在电子和光电器件的设计和优化中具有很大的灵活性。
Black phosphorus consists of stacked layers of phosphorene, a two-dimensional semiconductor with promising device characteristics. We report the realization of a widely tunable band gap in few-layer black phosphorus doped with potassium using an in situ surface doping technique. Through band structure measurements and calculations, we demonstrate that a vertical electric field from dopants modulates the band gap, owing to the giant Stark effect, and tunes the material from a moderate-gap semiconductor to a band-inverted semimetal. At the critical field of this band inversion, the material becomes a Dirac semimetal with anisotropic dispersion, linear in armchair and quadratic in zigzag directions. The tunable band structure of black phosphorus may allow great flexibility in design and optimization of electronic and optoelectronic devices.