Reduction of Interface States Density Due to Post Oxidation with Formation of AlGeO Layer at Al₂O₃/Ge Interface

Abstract

We have investigated the correlation between interface state density (D it) and interface structure of Al2O3/Ge with post thermal oxidation. D it around the midgap of Ge decreases with increment of oxidation temperature and saturates at more than 500°C. It is clarified that the AlGeO formation near the Al2O3/Ge interface occurs with increase in oxidation temperature. At more than 500°C, a stable Al6Ge2O13 is formed. On the other hand, GeO2 formation which is limited by the oxygen diffusion in the Al2O3 layer mainly occurred on the Al2O3 surface. Considering that Al2O3 layer prevents the oxygen diffusion compared to GeO2 layer, decomposition of GeO2 is dominant at Al2O3/Ge interface and GeO2 should be hardly formed at Al2O3/Ge interface. Therefore, AlGeO dominantly exists near the Al2O3/Ge interface and it surely lead to reduction of D it.

Annealing Effects on the Charging–Discharging Mechanism in Trilayer Al2O3/Ge/Al2O3 Memory Structures

“…Not all Ge is involved in this process, but a lot of small Ge clusters remain amorphous. 50,51 This is similar to the HfO 2 NC growth that penetrate in the Ge layer during the nanocrystallization process formation. In the case of HfO 2 Ge, HfO 2 crystallizes the first.…”

“…The crystallite nucleation is located mainly in the region of the Al 2 O 3 /Ge interface, but in the crystal growth processes, they can develop and penetrate also insight the Ge layer position in the direction of NC growth. Not all Ge is involved in this process, but a lot of small Ge clusters remain amorphous. , This is similar to the HfO 2 NC growth that penetrate in the Ge layer during the nanocrystallization process formation. In the case of HfO 2 Ge, HfO 2 crystallizes the first.…”