Interface studies of ALD-grown metal oxide insulators on Ge and III–V semiconductors (Invited Paper)

Abstract: Atomic layer deposited (ALD) HfO2/GeO x N y /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 1.3nm for 5nm HfO2 layers, and mid-gap density of interface states, D it =3×1011 cm−2 eV−1, 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. [Copyright &y& Elsevier]