RHEED patterns collected along the and axes: streaky pattern during GaAs buffer growth at 580 °C [(a),(b)]; GaAsN film growth: streaky pattern at 400 °C [(c),(d)], spotty pattern at 460 °C [(e),(f)], slightly spotty pattern at 520 °C [(g),(h)], and streaky pattern at 580 °C [(i),(j)].
Representative AFM images of GaAsN films grown at (a) 400 °C, (b) 460 °C, (c) 550 °C, and (d) 580 °C. The gray-scale ranges displayed are (a) 5 nm, (b) 200 nm, (c) 20 nm, and (d) 10 nm.
(Color online) Surface reconstructions observed during growth of GaAsN films: growth rate vs substrate temperature for (a) BEP ratio ; (b) BEP ratio ; and (c) BEP ratio . Solid (open) symbols denote 500 nm (10–100 nm) thick GaAsN films. The shaded regions indicate the conditions which lead to significant surface roughness, referred to as the “forbidden window.”
Schematic illustration of the critical island size, , for which the ES barrier leads to the nucleation of additional layers on top of the first-floor island. In (a), the island separation, , is less than , and islands coalesce together while remaining one monolayer in thickness, resulting in layer-by-layer growth. In (b), for , islands grow sufficiently large before coalescence, and new layers nucleate on top of the island, leading to multilayer growth.
(Color online) Large-scale STM images of 500 nm GaAs buffer grown using (a) and (b) , and high-resolution STM images of GaAs buffer grown using (c) and (d) , The color ranges displayed are (a) 1.8 nm, (b) 1.1 nm, (c) 1.3 nm, and (d) 1.7 nm.
(Color online) High-resolution STM images of 0.1 nm GaAsN grown at (a) 400 °C with , (b) 400 °C with , and (c) 607 °C with . The color ranges displayed are (a) 0.4 nm, (b) 1.5 nm, and (c) 2.3 nm. In each image, islands domains are indicated by arrows.
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