Fast surface states in germanium at low temperatures

E. Harnik*, Y. Goldstein, N. B. Grover, A. Many

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The characteristics of fast states on real germanium surfaces have been investigated at low temperatures. Measurements of the time-constant of relaxation processes involving the interaction between the fast states and the majority-carrier band were carried out on n-type samples as a function of temperature and surface potential using a pulsed field-effect technique. These were complemented with measurements of trapped charge density as a function of barrier height at various low temperatures. It is shown that the experimental results at such temperatures can be reconciled with room temperature data only by the assumption that both the energy of the recombination center, with respect to the conduction-band edge, and its capture cross-section for electrons are temperature dependent. The recombination level is found to move closer to the conduction band as the temperature is reduced while its capture cross-section for electrons decreases as exp(- Er kT), where the activation energy Er is about 0.2 eV. There are also indications of surface traps within 0.06 eV from the conduction band which have very small capture cross-sections for electrons. It has been observed that for values of the surface potential corresponding to strong depletion layers the relaxation phenomena are dominated by a process of enhanced generation of minority carriers, the mechanism of which is not understood.

Original languageEnglish
Pages (from-to)193-199
Number of pages7
JournalJournal of Physics and Chemistry of Solids
Volume14
Issue numberC
DOIs
StatePublished - Jul 1960

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