Absence of oxygen-vacancy-related deep levels in amorphous (Al2O3)_{1-x}(SiO2)_x: First-principles exploration of gate oxides in GaN-based devices
Absence of oxygen-vacancy-related deep levels in amorphous (Al2O3)_{1-x}(SiO2)_x: First-principles exploration of gate oxides in GaN-based devices
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非晶 (Al2O3)_{1-x}(SiO2)_x 中不存在与氧空位相关的深能级：GaN 基器件中栅极氧化物的第一原理探索
DOI：
10.1103/physrevapplied.14.014034
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发表时间：
2020
影响因子：
4.6
通讯作者：
A. Oshiyama and K. Shiraishi
中科院分区：
文献类型：
--
作者：
K. Chokawa;T. Narita;D. Kikuta;T. Kachi;K. Shiozaki;A. Oshiyama and K. Shiraishi
我们报告了密度泛函计算，澄清了非晶混合氧化物中氧空位的原子和电子结构，这是技术上有希望的栅极绝缘体候选者。我们用熔体-淬方案建立了非晶结构的微观模型，然后检查了所有可能的氧空位，并确定了总能量最小化的结构。我们发现一个明显的趋势，即在被较少原子包围的氧原子位置上形成的分子具有较低的形成能。更重要的是，我们发现单独被原子包围的原子不会在能隙中产生深能级，而被某些原子包围的原子则会产生深能级。这一理论发现有力地表明，非晶硅中的大多数是非电活性的，对设备操作没有太大的危害。此外，我们探索了从电活性到电非活性的结构转变的可能性。我们确定了这种转化的反应途径，并获得了相应的能垒。计算出的这些转变的发生率足够高，以确保在典型温度和时间下的热退火导致电活性的转变为非活性的，提供了作为栅极绝缘体比其他氧化物（如氧化铁）的进一步优势。
We report density-functional calculations that clarify the atomic and electronic structures of the oxygen vacancyin amorphousmixed oxides, which are promising candidates for the gate insulator intechnology. We construct microscopic models of the amorphous structure by the melt-quench scheme and then examine all the possible oxygen vacancies and determine the total-energy-minimizedstructures. We find a clear tendency for’s formed at oxygen sites surrounded by feweratoms to have a lower formation energy. More importantly, we find that asurrounded byatoms alone does not induce deep levels in the energy gap of, whereas’s surrounded by someatoms induce a deep level. This theoretical finding strongly implies that the majority of’s in amorphousare electrically inactive and not very harmful to device operation. Further, we explore the possibilities for structural transformation from the electrically activeto the electrically inactive. We identify reaction pathways for such transformations and obtain the corresponding energy barriers. The calculated occurrence rate for these transformations is high enough to ensure that thermal annealing at typical temperatures and times causes conversion of electrically active’s to inactive’s, providing a further advantage ofas a gate insulator over other oxides such asand.