A DOMINANT DEFECT AT THE Si/SiO_2 INTERFACE IN MOS STRUCTURE

The interface defects at the Si/SiO2 interface in ρ-type silicon （111） MOS structures have been studied by the DLTS method. A dominant defect Hit,（0.503） at the Si/SiO2 interface has been found. Its characteristics are （i） the average hole ionization Gibbs free energy △Gp≥0.503 eV; （ii） by changing the gate bias when the distance from Fermi level to the top of Si valence band at the Si/SiO2 interface is less than △Gp there is still the strong DLTS peak; （iii） its hole apparent activation energy increases with the dectease of the height of semiconductor surface potential barrier; and （iv） its hole capture process causes the multiexponential capacitance transience as a function of pulse width and the Hit（0.503） level are very difficult to be fully filled with the holes introduced by thepulst with alimited width. All above show that there is a continuous transition energy band between the energy bands of the covalent crystal silicon and the SiO2 in the Si/SiO2 systems formed by thermal

The interface defects at the Si/SiO_2 interface in ρ-type silicon (111) MOS structures have been studied by the DLTS method. A dominant defect H_(it),(0.503) at the Si/SiO_2 interface has been found. Its characteristics are (i) the average hole ionization Gibbs free energy △G_p≥0.503 eV; (ii) by changing the gate bias when the distance from Fermi level to the top of Si valence band at the Si/SiO_2 interface is less than △G_p there is still the strong DLTS peak; (iii) its hole apparent activation energy increases with the dectease of the height of semiconductor surface potential barrier; and (iv) its hole capture process causes the multiexponential capacitance transience as a function of pulse width and the H_(it)(0.503) level are very difficult to be fully filled with the holes introduced by thepulst with alimited width. All above show that there is a continuous transition energy band between the energy bands of the covalent crystal silicon and the SiO_2 in the Si/SiO_2 systems formed by thermal oxidation; the dominant defect H_(it)(0.503) is distributed in the transition region, and the distance of H_(it)(0.503) level from the top of the valence band increases with the distance from the silicon surface.