ELECTRONIC CONDUCTIVITY IN HIGHLY DOPED SIO2 BY MEANS OF ION-IMPLANTATION

Electrical transport properties of pure and phosphorus‐implanted SiO2 layers on n‐Si substrate are investigated. By means of multiple implantations and final etching‐off of the inhomogeneous top layer, uniformly doped SiO2 layers (L = 800 to 2400 Å) are achieved. Measurements of I–U‐characteristics reveal several different conductivity states of the samples referring to previous thermal annealing and electrical forming of unimplanted or implanted samples. For electrically unformed samples Fowler‐Nordheim tunneling across the interfaces prevailes (samples unimplanted) which changes to a bulk‐limited Pool‐Frenkel mechanism after implantation. The inherent trap density reaches between 5 × 1019 and 10 × 1020 cm−3 with respect to annealing. Electrically formed samples show SCL current behaviour of single‐ and double‐injection type with respect to carrier density electrically activated. Typically the mobility of carriers increases by a factor of 105 after implantation which leads to conductivity switching of samples at low voltages (UB = 2 to 20 V) as a consequence of double injection. The inherent trap density is lowered down to values of 1017 cm−3. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA