论文标题
硅亚稳态阶段的高热电性能：第一原理研究
High thermoelectric performance in metastable phase of silicon: a first-principles study
论文作者
论文摘要
在这项工作中，通过使用第一个$ - $原理计算与Boltzmann Transport Theorys相比，对Diamond $ - $ CUTIC SI（SI $ -I）的热传输特性和SI（Si $ -XII）的亚稳态R8期都进行了相对研究。亚稳定的Si $ - $ XII显示出比稳定的SI $ -I- $ I的晶格导热率低于300至500〜K，这归因于Si $ -y-$ XII的三$ $声子散射过程中的较强的声子散射。对于电子传输属性，尽管带有较小带隙（0.22 eV）的Si $ XII显示了较低的Seebeck系数，但各向异性$ n $$的电导率 - $ $ type si $ - $ xii沿$ x $ axis显示出相当大的值，这是由于沿此方向的电子有效质量小的质量质量。 $ n $$的功绩（$ zt $）的热电图的峰值 - $ n $ type si $ - $ xii高于$ p $$ - $ pype-type的峰值沿着同一方向。由于较低的晶格导热率和乐观的电导率，Si $ -xii表现出更大的最佳$ ZT $，而Si $ -i-i-i-i $ i- $ - $ i- $ p $$ - $ - $和$ n $ n $ ty- $ type-type掺杂。对于$ n $$-$ type si $ - $ xii，300、400和500 k的最佳$ zt $值可以达到0.24、0.43和0.63，沿着$ x $ x $ x $ x $ x $ x $ axis在载体浓度为$ 2.6 \ times10^{19} $，$ 4.1 \ times10^times10^19} $，以及$ 4.8 \ times10^{19} $ 〜cm $^{ - 3} $。报告的结果阐明了亚稳态Si可以集成到热电发电机上。
In this work, both thermal and electrical transport properties of diamond$-$cubic Si (Si$-$I) and metastable R8 phase of Si (Si$-$XII) are comparatively studied by using first$-$principles calculations combined with Boltzmann transport theory. The metastable Si$-$XII shows one magnitude lower lattice thermal conductivity than stable Si$-$I from 300 to 500~K, attributed from the stronger phonon scattering in three$-$phonon scattering processes of Si$-$XII. For the electronic transport properties, although Si$-$XII with smaller band gap (0.22 eV) shows lower Seebeck coefficient, the electrical conductivities of anisotropic $n$$-$type Si$-$XII show considerable values along $x$ axis due to the small effective masses of electron along this direction. The peaks of thermoelectric figure of merit ($ZT$) in $n$$-$type Si$-$XII are higher than that of $p$$-$type ones along the same direction. Owing to the lower lattice thermal conductivity and optimistic electrical conductivity, Si$-$XII exhibits larger optimal $ZT$ compared with Si$-$I in both $p$$-$ and $n$$-$type doping. For $n$$-$type Si$-$XII, the optimal $ZT$ values at 300, 400, and 500 K can reach 0.24, 0.43, and 0.63 along $x$ axis at carrier concentration of $2.6\times10^{19}$, $4.1\times10^{19}$, and $4.8\times10^{19}$~cm$^{-3}$, respectively. The reported results elucidate that the metastable Si could be integrated to the thermoelectric power generator.
