| Summary: | For realizing of Ge complementary metal-oxide-semiconductor with a Ge gate stack with thin equivalent oxide thickness, low interface state density (D<sub>it</sub>) and high reliability. In this paper, we examine the slow trap behaviors in the ALD high-k materials including Al<sub>2</sub>O<sub>3</sub>, Y<sub>2</sub>O<sub>3</sub>, HfO<sub>2</sub>, and La<sub>2</sub>O<sub>3</sub> on GeO<sub>x</sub>/Ge interfaces, where the GeOx interfacial layers are formed by plasma pre-oxidation. The C-V curves, Dit and slow trap density of the high-k/GeO<sub>x</sub>/nand pGe MOS capacitors are evaluated and compared. The Ge 3d spectra in X-ray photoemission spectroscopy are also compared among the Al<sub>2</sub>O<sub>3</sub>, Y<sub>2</sub>O<sub>3</sub>, HfO<sub>2</sub>, and La<sub>2</sub>O<sub>3</sub> on GeO<sub>x</sub>/Ge structures. It is found that Al<sub>2</sub>O<sub>3</sub> provides the lowest slow trap density for both electrons and holes in comparison with Y<sub>2</sub>O<sub>3</sub>, HfO<sub>2</sub>, and La<sub>2</sub>O<sub>3</sub> high-k films, while similar D<sub>it</sub> values are observed among the MOS interfaces with Al<sub>2</sub>O<sub>3</sub>, Y<sub>2</sub>O<sub>3</sub>, HfO<sub>2</sub>, and La<sub>2</sub>O<sub>3</sub>. The additional slow traps in the MOS capacitors with Y<sub>2</sub>O<sub>3</sub>, HfO<sub>2</sub>, and La<sub>2</sub>O<sub>3</sub> are attributable to any defects in the high-k films and/or the interfaces with GeO<sub>x</sub>.
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