论文标题
高度限制在未依存的KTAO3-Sandwiching异质结构的界面上的二维电子和孔气体共存
Coexisting two-dimensional electron and hole gases highly confined at the interfaces of undoped KTaO3-sandwiching heterostructures
论文作者
论文摘要
基于Perovskite Srtio $ _3 $（STO）的界面和表面中的二维电子气体（2DEG）表现出各种有趣的现象，用于开发氧化电子电子。最近，KTAO $ _3 $（KTO）具有巨大的潜力，被认为可以对新型设备产生更令人兴奋的效果和现象。在这里，通过第一原则的调查和分析，我们发现两种类型的共存的2DEG和2D孔气（2DHG）高度限制在未掺杂的sto/kto/batio $ _3 $异质结构的接口处，当时KTO $ m $达到crititcal值。这两个接口由（sro）$^0 $/（tao $ _2 $）$^+$和（ko）$^ - $/（tio $ _2 $）$^0 $用于a-type，以及（tio $ _2 $ _2 $）$^0 $/（ko）$/（ko）$^ - $^ - $^ - $^ - $^$ _2 $^$^$^$^+^0. 2D电子载体起源于ta- $ 5 d_ {xy} $状态，包括tao $ _2 $原子层，以及其他接口处的o- $ 2 p_x/p_y $ orbitals的孔载体。电子和孔有效质量分别为0.3 $ M_0 $和$ 1.06 \ sim 1.12 m_0 $，其中$ m_0 $是质量的免费电子，而2D载波浓度则为$ 10 ^{13} $ cm $ $ ^{ - 2} $。我们的分析表明，由于界面上的极性不连续性以及KTO层内的应力诱导的极化，界面2DEG和2DHG是同时形成的。这些可以激发新现象和新型设备的更多探索。
Two-dimensional electron gas (2DEG) in interfaces and surfaces based on perovskite SrTiO$_3$ (STO) has exhibited various interesting phenomena and is used to develop oxide electronics. Recently, KTaO$_3$ (KTO) shows great potential and is believed to host more exciting effects and phenomena toward novel devices. Here, through first-principles investigation and analysis, we find two types of coexisting 2DEG and 2D hole gas (2DHG) highly confined at the interfaces in undoped STO/KTO/BaTiO$_3$ heterostructures, when the KTO thickness $m$ reaches a crititcal value. The two interfaces are made by (SrO)$^0$/(TaO$_2$)$^+$ and (KO)$^-$/(TiO$_2$)$^0$ for the A-type, and by (TiO$_2$)$^0$/(KO)$^-$ and (TaO$_2$)$^+$/(BO)$^0$ for the B-type. The 2D electron carriers originate from Ta-$5 d_{xy}$ states at the interface including TaO$_2$ atomic layer, and the hole carriers from O-$2 p_x/p_y$ orbitals at the other interface. The electron and hole effective masses are 0.3$m_0$ and $1.06\sim 1.12 m_0$, respectively, where $m_0$ is mass of free electron, and the 2D carrier concentrations are in the order of $10 ^{13}$ cm$^{-2}$. Our analysis indicates that the interfacial 2DEG and 2DHG are simultaneously formed because of the band bending due to the polar discontinuity at the interfaces and the stress-induced polarization within the KTO layer. These could stimulate more exploration for new phenomena and novel devices.
