GaAs growth rate as a function of deposition temperature for a constant supersaturation condition. Growth rate is temperature dependent at low temperatures (kinetically limited) and temperature independent at high temperatures (transport limited). The kinetically limited growths were fit to a linear regression model to determine activation energy.
(a)-(f) Surface Nomarski contrast micrographs of a series of GaAs on Ge samples grown at varying depostion temperature (TD ). In all images, the scale bar is 50 μm.
RMS surface roughness as a function of deposition temperature as determined by AFM.
Ω-2θ XRD peak FWHM as a function of deposition temperature.
(a) GaAs growth rate as a function of thermodynamic supersaturation (β). (b) RMS surface roughness (left axis), and Ω-2θ xrd peak FWHM (right axis) as a function of β. TD was held at 720 °C for all depositions.
(220) bright field TEM images of the GaAs/Ge interface of the sample grown at (a) 775 °C and (b) 725 °C. A number of defects resembling anti-phase domain boundaries are visible along the GaAs/Ge interface in (a). These defects generally appear to self-annihilate after at most 100 nm. The sample grown at 725 °C exhibited a heterointerface completely free of APDs.
Ge concentration profile near the Ge/GaAs interface of an HVPE GaAs layer grown at 650 °C as measured by SIMS. Region A is the Ge substrate, while B-D are regions in the GaAs layer. Region B has been fit to Kavanagh's vacancy aided diffusion model, while region C was fit by a concentration independent, semi-infinite diffusion model.
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