磷化硼是一种具有高空穴迁移率的透明导电材料。这一承诺源于其低空穴有效质量。然而,BP具有相对小的2 eV间接带隙,这将影响其透明度。在这项工作中,我们计算研究了间接间隙的光吸收和声子限制的电子输运,以量化磷化硼作为\emph{p}型透明导体的潜力。我们发现,在可见光谱中,声子介导的间接光吸收很弱,并且在室温下,声子限制的空穴迁移率非常高(约900 cm $^2$ /Vs)。这种特殊的流动性来自低空穴有效质量和极声子模式的非常弱的散射的组合。我们合理化的弱散射的磷化硼相比,氧化物的离子键。我们认为这可能是\emph{p}型透明导电应用的非氧化物的一般优点。使用我们计算的属性,我们评估的透明导体的品质因数磷化硼,并表明,它超过了一个数量级,建立\emph{p}型透明导体,确认这种材料的潜力。
英文摘要:
Boron phosphide has recently been identified as a potential high hole mobility transparent conducting material. This promise arises from its low hole effective masses. However, BP has a relatively small 2 eV indirect band gap which will affect its transparency. In this work, we computationally study both optical absorption across the indirect gap and phonon-limited electronic transport to quantify the potential of boron phosphide as a \emph{p}-type transparent conductor. We find that phonon-mediated indirect optical absorption is weak in the visible spectrum and that the phonon-limited hole mobility is very high (around 900 cm$^2$/Vs) at room temperature. This exceptional mobility comes from a combination of low hole effective mass and very weak scattering by polar phonon modes. We rationalize the weak scattering by the less ionic bonding in boron phosphide compared to oxides. We suggest this could be a general advantage of non-oxides for \emph{p}-type transparent conducting applications. Using our computed properties, we assess the transparent conductor figure of merit of boron phosphide and shows that it exceeds by one order of magnitude that of established \emph{p}-type transparent conductors, confirming the potential of this material.
Self-energy corrected band-gap tuning induced by strain in the hexagonal boron phosphide monolayer
我们对二维六方磷化硼单层膜(2D-h-BP)的电子行为进行了第一性原理研究。通过沿a和b晶轴同时施加拉伸应变,系统各向同性变形。我们分析了带隙演化作为变形百分比的函数,范围从1%到8%。结果表明,该体系表现为直接带隙半导体,其价带峰和导带峰位于布里渊区的K点(1/3,1/3,0)。尽管施加了应变,但该行为不变。通过应用G 0 W 0方法校正了在标准DFT内计算的带隙低估。在两种方法中,带隙行为的趋势是相同的:对于低变形百分比,带隙以小斜率线性增长,并且在较高值下,带隙增长非常缓慢,并有达到饱和的趋势。因此,带隙对接近8%的变形的拉伸应变不太敏感。这种带隙行为的起源解释的投影态密度和电荷密度,它可以归因于库仑相互作用,和电荷重新分布由于施加的拉伸应变。为了研究载流子的迁移率,我们计算了电子和空穴的有效质量,发现两种载流子都有很高的迁移率。最后,每个应变系统的稳定性分析包括声子谱的计算,以确保动力学稳定性,弹性常数的计算,以评估机械稳定性,和结合能探索的结晶稳定性。结果表明,磷化硼单层膜在计算的拉伸应变下是稳定的。