Kang Youngho, Krishnaswamy Karthik, Peelaers Hartwin, Van de Walle Chris G
Materials Department, University of California, Santa Barbara, CA 93106-5050, United States of America.
J Phys Condens Matter. 2017 Jun 14;29(23):234001. doi: 10.1088/1361-648X/aa6f66. Epub 2017 Apr 26.
We perform first-principles calculations to investigate the electronic and vibrational spectra and the electron mobility of β-GaO. We calculate the electron-phonon scattering rate of the polar optical phonon modes using the Vogl model in conjunction with Fermi's golden rule; this enables us to fully take the anisotropic phonon spectra of the monoclinic lattice of β-GaO into account. We also examine the scattering rate due to ionized impurities or defects using a Yukawa-potential-based model. We consider scattering due to donor impurities, as well as the possibility of compensation by acceptors such as Ga vacancies. We then calculate the room-temperature mobility of β-GaO using the Boltzmann transport equation within the relaxation time approximation, for carrier densities in the range from 10 to 10 cm. We find that the electron-phonon interaction dominates the mobility for carrier densities of up to 10 cm. We also find that the intrinsic anisotropy in the mobility is small; experimental findings of large anisotropy must therefore be attributed to other factors. We attribute the experimentally observed reduction of the mobility with increasing carrier density to increasing levels of compensation, which significantly affect the mobility.
我们进行第一性原理计算，以研究β-GaO的电子和振动光谱以及电子迁移率。我们使用Vogl模型结合费米黄金定则来计算极性光学声子模式的电子-声子散射率；这使我们能够充分考虑β-GaO单斜晶格的各向异性声子光谱。我们还使用基于汤川势的模型来研究由于电离杂质或缺陷引起的散射率。我们考虑施主杂质引起的散射，以及诸如Ga空位等受主进行补偿的可能性。然后，我们在弛豫时间近似下，使用玻尔兹曼输运方程计算β-GaO在室温下的迁移率，其中载流子密度范围为10至10 cm。我们发现，对于高达10 cm的载流子密度，电子-声子相互作用主导迁移率。我们还发现迁移率的固有各向异性很小；因此，实验中发现的大各向异性必须归因于其他因素。我们将实验观察到的迁移率随载流子密度增加而降低归因于补偿水平的增加，这显著影响了迁移率。
