Figure 4
From: Magnification inferred curvature for real-time curvature monitoring
(a) Measurement of the curvature κ in tangential (blue) and sagittal (red) planes of a flat mirror repeated 105 times, and mounted on an optical vibration-free bench in order to get insights on the precision of our MIC-based tool. The distances \(\overline{OP}\) and \(\overline{AP}\) are those of the configuration in our MBE412 system (0.516 m and 0.678 m respectively). The incidence angle is either θ = 70° (left) or θ = 0° (right). The object is composed of a 1.6 × 1.6 cm2, 5 × 5 matrix of luminous spots. (b–d) In situ measurements of the curvature change during MBE growths. (b) Complete growth of a ~ 10 µm thick, 17 h long GaAs/AlGaAs EAM-VCSEL. The insert is the height scan of the grown structure with respect of the bare wafer measured by a P15 + KLA Tencor. (c) Focus on the controlled growth of the 1 eV GaInAsN sub-cell alloy of a tandem solar cell. The variation of the opening of the nitrogen plasma cell valve is shown in pink (right scale). (d) Focus on a InGaAs/GaAsSb tunnel junction where a strain relaxation is observed when the total structure grown thickness is ~ 700 nm.
