The impact of the surface on step-bunching and diffusion of Ga on GaAs (001) in metal-organic vapour phase epitaxy. (18th July 2016)

• Record Type: Journal Article
• Authors: Pristovsek, Markus; Poser, Florian; Richter, Wolfgang
• Is Part Of: Materials research express. Volume 3:Number 7(2016)
• Publication Date: 2016-07-18
• Subjects: diffusion -- surface reconstruction -- GaAs -- island nucleation -- step bunching -- 2D island growth mode -- step-flow growth; Materials science -- Research -- Periodicals; Materials science -- Periodicals; 620.11
• DOI: 10.1088/2053-1591/3/7/075902
• Languages: English
• ISSNs: 2053-1591

Abstract

Abstract: We studied diffusion by measuring step-bunching, island spacing, and the transition from step-flow growth to two-dimensional island growth of (001) GaAs in metal-organic vapour phase epitaxy and correlated them with the surface reconstruction measured by reflectance anisotropy spectroscopy. The V/III ratio had a small effect, while the square root of the growth rate was anti-proportional to the diffusion length. The thermal activation energy was about 2.3 eV on c ( 4 × 4 ) terraces and 1.6 eV on ( 2 × 4 ) domains at higher temperatures. Pronounced step-bunching coincided with large ( 4 × 2 ) domains at the step-edges, causing smoother steps for the [11̅0] misorientation. This Ga-rich reconstruction at the step-edges is needed for the Schwoebel barrier to induce step-bunching. At higher temperatures of ( 2 × 4 ) domains grow in size, the Schwoebel barrier reduces and nucleation becomes easier on this surface which reduces diffusion length and thus step-bunching.