DENSITY-OF-STATES AND RELAXATION SPECTRA OF ETCHED, H-TERMINATED AND NATURALLY OXIDIZED SI-SURFACES AND THE ACCOMPANIED DEFECTS

A new contactless method, the modulation CV-technique, is described wh ich allows a very sensitive determination of surface and interface sta te densities as well as the complete dispersion behaviour of these sta tes. With chemical H-termination surface state distributions may be ac hieved which are comparable to the best thermally oxidized surfaces. T he comparison of these two surfaces shows: Though these surfaces have the same distribution of interface traps D-it, they have a remarkable difference in the relaxation behaviour. The characteristic relaxation times are one to two orders of magnitude lower for thermally oxidized surfaces than for H-terminated ones. This is a hint that the matrix el ements which determine the interaction with the bands are different in the two different cases. The natural oxidation of H-terminated surfac es shows a quite different behaviour than thermal oxidation: Peaked de fect groups which are related to O-back-bonded Si-dangling-bonds grow and disappear during the first stages of oxidation. This is a hint to ordering processes during oxidation in addition to defect creation dur ing growth. These results supplement the general understanding of grow th mechanisms, The appearing defects during all treatments may be put into three categories: (1) normally distributed defects (Gaussian dist ribution); (2) reconstruction defects; (3) Boltzmann-distributed defec ts.