Atomic layer deposited (ALD) HfO2/GeOxNy/Ge(100) and Al2O3/In0.53Ga0.47As(100) 4 2 gate stacks
were analyzed both by MOS capacitor electrical characterization and by advanced physical characterization
to correlate the presence of electrically-active defects with chemical bonding across the insulator/
channel interface. By controlled in situ plasma nitridation of Ge and post-ALD annealing, the capacitance-
derived equivalent oxide thickness was reduced to 1.3 nm for 5 nm HfO2 layers, and mid-gap density
of interface states, Dit = 3 1011 cm2 eV1, was obtained. In contrast to the Ge case, where an
engineered interface layer greatly improves electrical characteristics, we show that ALD-Al2O3 deposited
on the In0.53Ga0.47As (100) 4 2 surface after in situ thermal desorption in the ALD chamber of a protective
As cap results in an atomically-abrupt and unpinned interface. By avoiding subcutaneous oxidation
of the InGaAs channel during Al2O3 deposition, a relatively passive gate oxide/III–V interface is
formed.