SPECT in cases of equilibrium disorders compared.

Local study of thickness-dependent electronic properties of ultrathin silicon oxide near SiO2/Si interface

“…However, in the case of amorphous Si oxide, an insulator with a bulk band gap of about 9 eV, the long-range disordered Si-O networks suppress the fine structures to be displayed, which is reflected in normalized dI/dV curves as a featureless flat region in the energy gap, except that the peaks appear near the CBM and VBM, due to the dramatically increased LDOS there. From the sharp increased peaks on both polarity sides, we can estimate the band gap of the oxide to be about 8.9 eV, which is in good agreement with the reported value for bulk SiO 2 and the value for the ultrathin Si oxide with a similar thickness reported by other authors [14].…”

“…The depth measured by STM is about 0.3 nm, as shown in figure 1(c), corresponding to a single biatomic step on Si(1 1 1). Though the tunnelling barrier varies between Si and SiO 2 , we verify this value separately by contact-atomic force microscope(c-AFM), which is in agreement with the reported observation [14]. Since a large strain exists at the interface between Si oxide and Si, a compressive stress in the interfacial ultrathin Si oxide tends to maintain the monolayer thickness similar to that of the Si substrate, ∼0.3 nm.…”

“…Though some local studies by STM have focused on the electrical properties of ultrathin Si oxide [13][14][15][16], experimental results such as energy gap evolution and gap states on a nanometre scale still remain elusive. To study the thicknessdependent electronic properties of the initially grown ultrathin Si oxide by STM/STS, the major challenge is that reliable results are always based on in situ probing of the sample by the same tip without further modifying and transferring the sample after fabrication, so as to avoid any unexpected changes.…”