Effects of Boron Doping on the Bulk and Surface Acoustic Phonons in Single-Crystal Diamond
Effects of Boron Doping on the Bulk and Surface Acoustic Phonons in Single-Crystal Diamond
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DOI：
10.1021/acsami.2c10879
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发表时间：
2022-09-09
影响因子：
9.5
通讯作者：
Balandin, Alexander A.
中科院分区：
文献类型：
--
作者：
Guzman, Erick;Kargar, Fariborz;Balandin, Alexander A.
本文报道了用布里渊-曼德琉散射光谱研究未掺杂和掺硼单晶金刚石薄膜中的体声子和表面声子的结果。用拉曼光谱监测了同一组样品中光学声子的演化。结果表明，随着硼掺杂浓度的增加，声学声子的频率和群速度呈非单调下降，表现出明显的声子软化现象。简并掺杂金刚石中的剪切水平和高频伪纵向声学声子的速度的变化，与未掺杂金刚石中的相比，分别为15%和12%。作为硼掺杂的结果，体纵向和横向声学声子的速度相应地降低。光学声子的频率在低硼浓度下不受影响，但在高掺杂水平下经历了强烈的下降。原始和高掺杂样品的声子能带结构的密度泛函理论计算证实了作为金刚石中硼掺杂的结果的声子软化。重掺杂金刚石是一种很有前途的超宽带隙电子学材料，研究结果对重掺杂金刚石的热输运具有重要意义。
We report the results of the investigation of bulk and surface acoustic phonons in the undoped and boron-doped single-crystal diamond films using the Brillouin-Mandelstam light scattering spectroscopy. The evolution of the optical phonons in the same set of samples was monitored with Raman spectroscopy. It was found that the frequency and the group velocity of acoustic phonons decrease nonmonotonically with the increasing boron doping concentration, revealing pronounced phonon softening. The change in the velocity of the shear-horizontal and the high-frequency pseudo-longitudinal acoustic phonons in the degenerately doped diamond, as compared to that in the undoped diamond, was as large as similar to 15% and similar to 12%, respectively. As a result of boron doping, the velocity of the bulk longitudinal and transverse acoustic phonons decreased correspondingly. The frequency of the optical phonons was unaffected at low boron concentration but experienced a strong decrease at the high doping level. The density-functional-theory calculations of the phonon band structure for the pristine and highly doped samples confirm the phonon softening as a result of boron doping in diamond. The obtained results have important implications for thermal transport in heavily doped diamond, which is a promising material for ultra-wide-band-gap electronics.