Variation of Misfit Strain in ZnSe Heteroepitaxial Layers with Temperature, Layer Thickness and Growth Temperature

The temperature variation of misfit strain in ZnSe layers grown on GaAs(100) substrates has been measured at 80∼600 K for layer thicknesses of 0.2∼4.0 µm by X-ray diffraction. Layers as thin as 0.2 µm grow coherently on the substrate and the coherency holds even for low temperatures. Strain-free layers at room temperature include the two-dimensional expansive strain with ε ⊥≡(a ⊥-a 0)/a 0≈-0.03% at 80 K; layers including the two-dimensional compressive strain with ε ⊥≈+0.03% at room temperature become strain free at 80 K. The X-ray analysis is consistent with low-temperature reflection spectra.