Character of surface states at GaAs surfaces

Abstract

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.

GaAs–Anodic Oxide Interface Examination by Deep–Level Transient Current Spectroscopy

“…Evidently, with the high-resistivity interface layer being present a t the interface, one cannot populate the surface states with electrons by means of a saturating pulse and the surface states do not respond to the excitation. There is an independent direct evidence for the existence of such an interface layer with significant deviations from stoichiometry, as was stated by Kreutz [17]. We hope to have demonstrated how to explore the electronic properties of the defects in this layer by DLTS experiments.…”

“…Some comments are necessary concerning lacking evidence for the 77-shaped continuous distribution of the GaAs-oxide interface states from DLTS, the distribution of which was well established both theoretically and experimentally, see the excellent review by Kreutz [17] and the papers by Spicer et al [8 to 101. From this point of view the 360K peak is expected to be superimposed on a broad DLTS spectrum of fast surface states.…”

Development of ultrafast broadband electronic sum frequency generation for charge dynamics at surfaces and interfaces

“…Surface sites accessible for native oxidized p-type GaAs were found to be 3.0 × 10 13 cm −2 (see the supplementary material), which is in agreement with the value reported in the literature. 103,104 A fluence of 10 µJ/cm 2 fully populates all the surface states for p-type oxidized GaAs, as seen in the supplementary material. Thus, the population rate constants at 660 nm and 745 nm were found to be similar with a value of 0.012 (±0.002) × 10 12 s −1 cm 2 .…”

Photoassisted tunneling from free-standing GaAs thin films into metallic surfaces

“…The results are analyzed using a new model which incorporates photovoltage, 10 surface recombination 18 and the energy dependence of the density of surface states 19 together with the bias dependence of the tunnel barrier height. 20 For a gold (non-magnetic) surface, the interpretation of the results is relatively simple as the density of empty states depends only weakly on energy.…”