The growth of thin PbO layers on lead films

Eldridge, J. M.

doi:10.1016/0039-6028(73)90142-8

Cited by 8 publications

(2 citation statements)

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“…Lead.--A detailed study of lead oxidation has been carried out as part of the tunneling device investigation at IBM (19)(20)(21). E]lipsometry was used to follow the growth rate of PbO on a single-crystal lead film at temperatures between -90 ~ and 150~ Comparative oxide thicknesses determined by ellipsometry, x-ray absorption, and electron tunneling all agreed within an order of magnitude.…”

Section: I00 -mentioning

confidence: 99%

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Low Temperature Oxidation of Metals and Semiconductors

Fehlner

1984

J. Electrochem. Soc.

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The growth of oxide films on metals and semiconductors at low temperatures has been interpreted using the Cabrera-Mott theory which assumes a uniform oxide structure. Kinetic data taken from the literature were introduced into the Ghez integration of the Cabrera-Mott equation. Results were found to correlate with a division of oxides into network formers, intermediates, and modifiers. The network formers and intermediates were best fit by inverse logarithmic kinetics (Cabrera-Mott), while the modifiers appeared to follow direct logarithmic kinetics. Values of activation energy for ion movement, the number of potentially mobile ions, and the self-induced voltage across the oxide have been derived for the network forming and intermediate oxides. These values are compared with those obtained from other experiments.The field of low temperature oxidation has been experimentally handicapped by a lack of extensive data on simple systems. Several reasons account for this paucity of data: the difficulty of measurements, poor reproducibility of metal samples, little control of impurities (especially water vapor), and incomplete characterization of the product oxide. Fortunately, this situation is changing as semiconductor techniques and surface analytical methods are applied to the problem. As a result, data over an extensive temperature and pressure range are becoming available.Analysis and interpretation of such kinetic data is the next difficulty. Historically, linearity of a plot on graph paper has been taken to be indicative of a particular mechanism. However, it has become apparent that for low temperature oxidation, both direct logarithmic (x vs. log t, where x is oxide thickness and t is time) and inverse logarithmic kinetics (1/x vs. log t) can often fit the same set of data.One resolution of this dilemma is to examine the principles upon which each derived rate equation is based and calculate values for physical quantities which are measurable in other experiments. Many descriptive models of low temperature oxidation have been put forward, but the Cabrera-Mott theory (1) stands out as having proven validity. For this reason, it is emphasized here as the basis for interpreting kinetic data from low temperature oxidation.The Cabrera-Mott approach (1) assumes a quasiequilibrium of electrons tunneling across the thin oxide. Some electrons are trapped on oxygen sites at the oxide-gas interface, setting up a spontaneous voltage which is taken to be constant. The resulting field aids cation incorporation at the metal-oxide interface. This process is assumed to be rate limiting. Fehlner and Mott (2) have applied these ideas to anion incorporation at the oxide-gas interface and conclude that the same equation may be applied to both anion and cation movement.In experiments, oxide thickness x is measured as a function of time, t, while pressure P, temperature T, number of potentially mobile ions N, activation energy for ion movement W, voltage across the oxide V, ion-jump distance 2a, frequency of vibration v, and oxide vol...

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Section: I00 -mentioning

confidence: 99%

“…Eldridge and Dong (19,20) had calculated values of u and x,, but they applied them to an oxidation model based on piezoelectric effects. In the present approach, these values of u and x, were analyzed using Eq.…”

Section: Germanium I00 -mentioning

confidence: 99%