Interface properties of Al–Al2O3–Ge MIS capacitors and the effect of forming gas annealing

•Study of hydrogen annealing in p-type Ge/Al2O3/Al capacitors•Conductance technique at low temperatures•Significant passivation of interface traps near the valence band edge.

In this work the effect of Al deposition process and the subsequent forming gas annealing on the interfacial properties of Al/Al2O3/p-Ge MOS capacitors is studied. Al2O3 has been deposited by ALD at 300 °C. There is evidence that Al deposition by e-beam evaporation affects the structure and composition of the Al2O3/Ge interface by decomposing the GeOx interfacial layer and leading to interfacial non-uniformities reflected in conductance measurements. Forming gas annealing is able to passivate interface traps near the valence band edge possibly originating from Al2O3–Ge dangling bonds during the dielectric deposition. However it is unable to passivate interface traps near the midgap possibly originating from e-beam evaporation radiation damage.

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