Effect of nanometer-scale corrugation on densities of gap states and fixed charges at the thermally grown SiO[sub 2]/Si interface.

Effect of nanometer-scale corrugation on gap state and fixed charge densities at the SiO[sub 2]/Si interface in Si (001) metal-oxide-semiconductor (MOS) capacitors has been studied by capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements. As the interface corrugation, a high density of Si protrusions, composed of a microscopic (001) plane at the top and high-index planes [typically (115) planes] at the sides, were formed by a microscopic selective oxidation technique developed by the authors. By changing the selective oxidation condition, the area ratio of the top and side planes was varied. As a result, it was found that each of C-V and G/ω-V curves showed a mixture of two curves with different flatband voltages. This reflects that the interface fixed charge density at the side high-index planes is larger than that at the top (001) plane, similar to previous reports for classical MOS capacitors with a macroscopic flat interface. Furthermore, it was found that the side high-index interface has a higher gap state density than the top (001), also similar to the previous macroscopic results. Such orientation dependence of gap state and fixed charge densities in the nanometer regime will play a significant role in electrical properties of ultrasmall Si devices, which accompany a relatively large area of curved interfaces. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]