(Color online) Measured and model fits of the ellipsometric parameters, Ψ and Δ, at θ = 70° for thin films on GaAs(100) grown to a thickness of (a) 0.62 nm (4 cycles) and 10 nm (80 cycles) using plasma-assisted ALD, and to a thickness of (b) 0.62 nm (8 cycles) and 5 nm (80 cycles) using thermal ALD.
(Color online) Dependence of the bulk Al2O3 film thickness and interfacial layer thickness upon the number of ALD cycles for thermal and plasma-assisted ALD.
(Color online) SE map showing the uniformity of film thickness over the surface of the 4-in. wafer for a plasma-assisted ALD film grown using four cycles.
(Color online) XPS of Al2O3-films (a) grown on GaAs(100) using plasma-assisted ALD for different thicknesses. (b) Detail of the low binding energy region for a 4 nm-thick film. (c) Gaussian fit of Al-2s for a 4 nm-thick plasma ALD thin film. (d) Gaussian fits of O-1s for a 10 nm-thick thermal ALD thin film, and for 10 nm- and 1 nm-thick plasma ALD thin films.
Atomic ratio, O:Al, calculated from the relative intensities of Al-2s and O-1s core-level peaks plotted as a function of the number of ALD cycles. The broken line marks the expected stoichiometric ratio of 1.5.
(Color online) XPS core-level spectra of Ga-3p (a)–(d) and As-3p (e)–(h) and their deconvolution for thermal (A) and plasma (B) ALD-Al2O3 films grown on s.i. GaAs(100) using the number of cycles as given in the figure. (Ga,As)-oxide related peaks of the interfacial layer are marked as oxid. p3/2 and oxid. p1/2.
(Color online) Thermal cycling dependence of stress in 5 nm-thick plasma ALD-Al2O3 thin films grown on 2-in. (a) GaAs(100) and (b) Si(100) substrates at 300 °C. Measurement points correspond to 4 consecutive thermal cycles. For the sake of comparison, the y-axis range has been kept constant for all plots.
Thermal cycling dependence of stress in 5 nm-thick thermal ALD-Al2O3 thin films grown on 2-in. (a) GaAs(100) and (b) Si(100) substrates at 300 °C.
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