(Color online) AFM image (signal amplitudes) of the top surface of the investigated structures. Left: planar GaAs; right: QD GaAs structure: a) large scale organization of the surface (30 × 30 μm), b) zoom-in to 1 × 1 μm area. Bottom panels show cross-section through the corresponding height images.
Photographs of water droplet silhouette on top of epitaxial structures; left panel corresponds to planar GaAs (epitaxial), right to QD GaAs: a) sample within 30 min from removal from MOVPE reactor; b) sample air-stored for 7 days; c) sample air-stored for about 1 month; d) sample air-stored for several months.
Photographs of water droplet silhouette on top of epitaxial structures; left panel corresponds to planar GaAs, right to QD GaAs: a) sample after oxygen plasma treatment; b) sample after oxygen plasma treatment and subsequent storage for 1 day; c) sample after HCl etching.
(Color online) Summary of WDCA measured on air-aged samples and after treatment. Measurement series are corresponding to individual samples with different growth conditions and morphologies. The square markers correspond to epi-ready wafers, circular to planar growths, and triangular to quantum dot samples. The point corresponding to an epitaxially grown structure with a GaAs cap reported in the > 6 month aged session corresponds to ∼ 3 years of aging. Data points correspond to the average value measured on multiple drops deposited on the sample surface.
WDCA on epi-ready wafer by WaferTech: a) and b) as taken from the box; c) after plasma oxidation and subsequent HCl treatment; d) after HCL etching and subsequent plasma oxidation.
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