Properties of AlN Thin Films on p-Ge Deposited by Thermal Atomic Layer Deposition

The electrical and interfacial properties of atomic layer deposited AlN on p-Ge were investigated. A very large capacitance–voltage (C–V) hysteresis at 1 MHz was observed, resulted from the presence of high density of slow traps that is associated with the GeO volatilization. Nonetheless, well-behaved C–V characteristics with minimal frequency dispersion and the absence of bumps near the flat-band voltage were obtained except 1 MHz, implying that the AlN passivation occurred near the AlN/Ge interface. Parallel conductance values showed that both slow and fast states were located within a narrow energy range. X-ray photoelectron spectroscopy (XPS) spectra revealed that large amount of oxygen atoms are present near the AlN/Ge interface. Above the AlN critical thickness, the strong Al–Al bond in the Al 2p spectra was observed, which could be explained by the strain relaxation due to the lattice mismatch between AlN and Ge.