Electronically induced modifications of a-Si:H(P) films by scanning tunneling microscopy

Elmar Hartmann, Marian Enachescu, Frederick Koch, Gerhard Krötz, Gerhard Müller, Rolf Jürgen Behm

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Samples fabricated of n-type, hydrogenated amorphous Si layers deposited on heavily doped, p-type crystalline Si substrates, forming a p-n heterojunction, were modified and imaged by use of a scanning tunneling microscope (STM). Applying a sufficiently large forward bias with respect to the internal p-n junction, the high current density caused by the tip induces changes in the coordination of dopant and Si sites within the amorphous film affecting the Fermi level position in the mobility gap (generalized autocompensation model). We distinguish between structural modifications in a near surface region reducing the layer conductivity and changes in the bonding arrangements through the entire coating. In the latter case, the p-n junction is modified resulting in an exponentially increased hole-injection from the substrate. I-V characteristics obtained by STM indicate a threshold switching behavior from a high-impedance to a low-impedance state and a memory effect.

Original languageEnglish
Pages (from-to)1067-1070
Number of pages4
JournalJournal of Non-Crystalline Solids
Issue numberPART 2
StatePublished - 1991
Externally publishedYes


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