Charge trapping in SiO2 layers implanted with rare earth and Ge ions

Metal-oxide-silicon (MOS) structures containing different rare earth and germanium ions exhibit strong luminescence from 300-1540 nm. This emission is very interesting from the viewpoint of the silicon-based light-emitting devices formation. Charge trapping behaviour in Ge and rare earth (Ce, Eu, Gd, Tb, Er and Tm) enriched SiO2 during high field electron injection corresponding to operation of the light-emission devices has been studied. Employing of constant current injection regime and high frequency C-V characteristics it was shown that embedment of rare earth impurities into dioxide matrix results in formation of similar system of charge traps with following capture cross section 2..3e-15 cm2 for electron and >1e-14 cm2 for holes. In various rare earths doping the amphoteric charge traps with distributed capture cross section in range from 1e-15 to 1e-17 cm2 is observed. Observed system of the traps is considerable different from one in the Ge implanted structures. For distributed traps an increase of injected current into the dielectric results in increase to positive charge trapping. Model of charge trapping in the defect shell located around rare earth inclusions inside of dioxide matrix is discussed.