TUNNELING IN ULTRATHIN SIO2 LAYERS ON SILICON - COMMENTS ON DISPERSION-RELATIONS FOR ELECTRONS AND HOLES

A fundamental asymmetry between the tunneling probabilities for electrons and holes has been observed in ultrathin SiO2 layers (20-30 Å). These probabilities have been measured on the same MOS samples using a new experimental technique combining dark characteristics with measurements of photocurrent suppression by the SiO2 layer. Interpretation by Franz dispersion relations using conduction and valence band energies appropriate to thick SiO2 films is not possible even assuming different effective masses in the two bands. This may be attributed to the distortion of the energy bands in the SiO2 caused by the presence of positive oxide charge. © 1979.