Surface states in GaAs tunnel MIS structures

Alternating current and step pulse field effect on n‐type GaAs with real surfaces of natural oxides are investigated as a function of temperature, electric field strength, frequency, and surface potential. The sign of the field induced changes of surface conductivity implies depletion layers in the surface. The kinetics of the field effect measurements show complex behaviours including a field induced hysteresis, a frequency dispersion, and a temperature dependence of the field effect curves. The interface state density at the GaAs–oxide interface is derived from the combination with thermally stimulated current measurements of the field induced conductivity changes. The density of interface states per energy interval consists of a continuous distribution with a minimum in the upper half of the energy gap.

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Character of surface states at GaAs surfaces

Kreutz

1979

Phys. Stat. Sol. (a)

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The analysis of field effect measurements and of thermally stimulated currents allows t o derive the general shape of the distribution of surface states for GaAs surfaces. The density of fast snrface states consists out of a continuous distribution with a minimum near the niiddle of the energygap as well as increasing tails towards the band edges. About the middle of the forbidden gap a peaking distribution is superposed to the continuous distribution. The response to physical and chemical influence allows to discriminate between intrinsic and extrinsic surface states. This distribution of surface states qualitatively yields a satisfactory description of the experimental results. Die Analyse von Messungen des Feldeffektes und [thermisch stimulierter Strome liefert dasGaAs-Oberflachen das Termspektrum der Oberfliichenzustande. Die Dichte der Oberfliichenzustande zeigt ein Minimum nahe der Mitte der verbotenen Zone und steigt zu den Bandkanteii an. Etwa in der Mitte der verbotenen Zone ist dem kontinukflichen Termspektrum eine Gruppe energetisch verteilter Oberflachenstande uberlagert. Die Anderungen der Termspektren gegenuber physikalischen und chemischen Einfldssen erlaubt, zwischen intrinsischen und extrinsischen Oberflachenzustanden zu unterscheiden. Das Termspektrum der Oberflachenzustande beschreib t qualitativ befriedigend die experimentellen Ergebnisse.

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Surface states in GaAs tunnel MIS structures

Cited by 16 publications

References 16 publications

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Character of surface states at GaAs surfaces

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