Eur. Phys. J. B 7, 1-4 (1999)
https://doi.org/10.1007/s100510050583

Explanation of multiplet spots in low-energy electron diffraction patterns of clean GaN{0001}-1x1 surfaces

Laboratorium für Festkörperphysik, Gerhard-Mercator-Universität-Duisburg, 47048 Duisburg, Germany

Received: 22 June 1998
Revised: 8 September 1998
Accepted: 9 September 1998
Published online: 15 January 1999

Abstract

Clean, ordered, and stoichiometric GaN{0001}-1x1 surfaces are obtained after exposure to a Ga-flux followed by annealing in ultrahigh vacuum (UHV), after desorption of a Ga layer deposited at room-temperature or after nitrogen ion-bombardment and annealing in UHV. Samples annealed at temperatures above approximately 850°C display 1x1 low-energy electron diffraction patterns. As a function of electron energy, the normal-order spots split into circular sextets. These multiplet rings periodically expand and coalesce. This observation is explained by oppositely oriented, regular step arrays in the [1000]-, [0100]- and [0010]-directions on the GaN{0001} surfaces. Quantitative analysis of the data gives terrace widths of Å and step heights of Å . The observations suggest faceting or the "development" of growth spirals with steps heights of two Ga-N bilayers by thermal etching.