The interface between hafnium oxide grown by atomic layer deposition and (100) GaAs treated with HCl cleaning and (NH 4 ) 2 S passivation has been characterized.Synchrotron radiation photoemission core level spectra indicated successful removal of the native oxides and formation of passivating sulfides on the GaAs surface. Layer-bylayer removal of the hafnia film revealed a small amount of As 2 O 3 formed at the interface during the dielectric deposition. Traces of arsenic and sulfur out-diffusion into the hafnia film were observed after a 450 o C post-deposition anneal, and may be the origins for the electrically active defects. Transmission electron microscopy cross section images showed thicker HfO 2 films for a given precursor exposure on S-treated GaAs versus the SLAC-PUB-12802 September 2007Submitted to Journal of Applied Physics 2 non-treated sample. In addition, the valence-band and the conduction-band offsets at the HfO 2 /GaAs interface were deduced to be 3.18 eV and a range of 0.87-0.97 eV, respectively. It appears that HCl+(NH 4 ) 2 S treatments provide a superior chemical passivation for GaAs and initial surface for ALD deposition.

This study reports on the first experimental observations of electrically biased paramagnetic defects at 800 °C N2 annealed HfxSi1−xO2 (x=0.4, and 0.6)/(100)Si and HfO2/(100)Si interfaces in metal oxide silicon structures. These defects are examined by electrical-field controlled electron spin resonance (ESR) and correlated with capacitance-voltage (C-V) analysis. Distributions of ESR measured density of interface traps (ESR-Dit), Pb0 and Pb1, exhibit distinct charge humps and peaks in the Si bandgap with maximum defect density of 0.9–1.9×1012 cm−2 eV−1 in the Hf0.4Si0.6O2/Si interface. Three Pb0 and one Pb1 charged ESR-Dit peaks with density of 1.7–2.8×1012 cm−2 eV−1 are observed in the Hf0.6Si0.4O2/Si interface. Cross-sectional transmission electron microscopic images show decreasing interfacial layer (IL) thickness with increasing hafnium composition (x) at the HfxSi1−xO2/Si interface. The roughest IL observed at the HfO2/Si interface may have contributed to an ESR-Dit of Pb0 greater than 2×1013 cm−2 eV−1 and a pinned Fermi level near the midgap. It appears that the energy distributions of interface defects in HfxSi1−xO2/Si and HfO2/Si have different signatures compared to those at SiO2/Si interface, especially the charged peak near the midgap.