Devenson Jan, Norkus Ričardas, Juškėnas Remigijus, Krotkus Arūnas
Opt Lett. 2021 Aug 1;46(15):3681-3684. doi: 10.1364/OL.425271.
Thinner than 10 nm layers of bismuth (Bi) were grown on (111) Si substrates by molecular beam epitaxy. Terahertz (THz) radiation pulses from these layers excited by tunable wavelength femtosecond optical pulses were measured. THz emission sets on when the photon energy exceeds 0.45 eV, which was explained by the semimetal-to-semiconductor transition at this Bi layer thickness. A THz signal has both isotropic and anisotropic components that could be caused by the lack of balance of lateral photocurrent components and the shift currents, respectively.
通过分子束外延在（111）硅衬底上生长了厚度小于10纳米的铋（Bi）层。测量了由可调谐波长飞秒光脉冲激发的这些层产生的太赫兹（THz）辐射脉冲。当光子能量超过0.45电子伏特时，太赫兹发射开启，这可由该铋层厚度下的半金属到半导体转变来解释。太赫兹信号具有各向同性和各向异性分量，分别可能是由横向光电流分量和位移电流缺乏平衡导致的。
