Paramagnetic Point Defects In (100)Si/Laalo3 Structures: Nature And Stability Of The Interface

The atomic nature of the interface in (100)Si/LaAlO3 structures with nanometer-thin amorphous LaAlO3 layers of high dielectric constant (K), deposited directly on clean (100)Si by molecular beam deposition at similar to 100 degrees C, was assessed through probing of paramagnetic point defects. On the as-grown samples K-band electron spin resonance indicated the absence of a Si/SiO2-type interface in terms of the archetypal Si-dangling bond-type Si/SiO2 interface defects (P-bO, P-b1). With no P-b-type defects observed, this state is found to persist during subsequent annealing (1 atm N-2 or 5% O-2 in N-2 ambient) up to the temperature T-an similar to 800 degrees C, referring to a thermally stable abrupt Si/LaAlO3 interface, quite in contrast with other high-K metal oxide/Si structures. However, in the range T-an similar to 800-860 degrees C a Si/SiO2-type interface starts forming as evidenced by the appearance of P-b0 defects and, with some delay in T-an, the EX center-a SiO2 associated defect, attesting to significant structural/compositional modification. The peaking of the defect density versus T-an curves indicates the SiOx nature of the interlayer to break up again upon annealing at T-an >= 930 degrees C, possibly related to crystallization and/or degrading silicate formation. No specific LaAlO3-specific point defects could be traced. (c) 2007 American Institute of Physics.