Full-band polar optical phonon scattering analysis and negative differential conductivity in wurtzite GaN
Full-band polar optical phonon scattering analysis and negative differential conductivity in wurtzite GaN
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DOI：
10.1103/physrevb.62.15754
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发表时间：
2000-12
影响因子：
3.7
通讯作者：
C. Bulutay;B. Ridley;N. Zakhleniuk
中科院分区：
文献类型：
--
作者：
C. Bulutay;B. Ridley;N. Zakhleniuk
氮化镓在高场电子应用中具有很好的特性。为了仔细研究这些与输运相关的性质，首先需要很好地表征这种材料的主要散射机制。在寻找块体GaN中的布洛赫振荡时，我们的目标是进行需要非常高能量的全波段散射分析，而抛物近似远不适用。为此，我们首先利用最新的实验数据作为输入，基于经验赝势方法获得纤锌矿GaN导带的精确带结构。我们计算了与室温相关的纵向类光学和横向类光学极性声子模式沿几个（高对称）方向的散射率，从区域中心的传导带最小值到每个方向上的互反晶格矢量的一半。我们观察到邻近山谷的位置和路径的对称性对散射率起决定性作用。在块状纤锌矿GaN中观测布洛赫振荡是由于极性散射率非常大。然而，在2.3 MV/cm以上的电场中，纤锌矿GaN存在由能带结构负有效质量部分驱动的负差分电导率的可能性。
GaN has promising features for high-field electronics applications. To scrutinize these transport-related properties, primarily the dominant scattering mechanism in this material needs to be well characterized. In the quest for Bloch oscillations in bulk GaN, our aim is to conduct a full-band scattering analysis requiring very high energies where parabolic approximation is far from applicable. For this purpose, we first obtain an accurate band structure for the conduction band of wurtzite GaN based on the empirical pseudopotential method, using the most recent experimental data as the input. We compute the scattering rate, relevant up to room temperatures, due to longitudinal-optical-like and transverse-optical-like polar phonon modes along several (high-symmetry) directions, from the conduction band minimum at the zone center to the half of the reciprocal lattice vector in each direction. We observe that the location and the symmetry of the neighboring valleys to the route play a decisive role on the scattering rates. The observation of Bloch oscillations in bulk wurtzite GaN is doomed by the very large value of the polar scattering rate. However, there exists the possibility of a negative differential conductivity driven by the negative effective mass part of the band structure for fields above 2.3 MV/cm for wurtzite GaN.