Germanium (Ge) has gained great attention not only for future nanoelectronics but for back-end of line (BEOL) compatible monolithic three-dimensional (M3D) integration recently. For high performance and low power devices, various high-k oxide/Ge gate stacks including ferroelectric oxides have been investigated. Here, we demonstrate atomic layer deposited (ALD) polycrystalline (p-) HfO ₂ /GeO _X /Ge stack with an amorphous (a-) HfO ₂ capping layer. The consecutively deposited a-HfO ₂ capping layer improves hysteretic behaviors ( ${\Delta } {V}$ ) and interface state density ( $\text{D}_{\mathrm{ it}}$ ) of the p-HfO ₂ /GeO _X /Ge stack. Furthermore, leakage current density ( ${J}$ ) is significantly reduced $(\times 100)$ by passivating leakage paths through grain boundaries of p-HfO ₂ . The proposed HfO ₂ layer with the graded crystallinity suggests possible high-k/Ge stacks for further optimized Ge MOS structures.

中文翻译：

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用于高k / Ge MOS栅堆叠的渐变晶体HfO 2栅介电层

锗（Ge）不仅受到未来纳米电子学的关注，而且最近还受到与后端（BEOL）兼容的单片三维（M3D）集成的关注。对于高性能和低功率器件，已经研究了包括铁电氧化物的各种高k氧化物/ Ge栅叠层。在这里，我们展示 了具有非晶（a-）HfO ₂覆盖层的原子层沉积（ALD）多晶（p-）HfO ₂ / GeO _X / Ge叠层 。连续沉积的a-HfO ₂覆盖层可改善磁滞行为（ $ {\ Delta} {V} $ ）和界面状态密度（ $ \ text {D} _ {\ mathrm {it}} $ p-HfO ₂ / GeO _X / Ge堆栈）。此外，漏电流密度（ $ {J} $ ）大大减少了 $（\次100）$ 通过钝化穿过p-HfO _2的晶界的泄漏路径 。拟议的具有渐变结晶度的HfO ₂层表明，可能存在用于进一步优化的Ge MOS结构的高k / Ge叠层。