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The orientation dependence of phase separation has been examined in detail in InGaAsP layers grown by liquid phase epitaxy on (001), (110), (111)In and (123) InP substrates. It is shown that phase separation is two-dimensional in nature and does not occur along the growth direction for the cases examined. Further, phase separation takes place along the soft directions lying in the growth plane. These results very strongly suggest that phase separation evolves at the surface while the layer is growing.CuPt-type ordering characteristics of InGaAsP layers are presented. In addition, the Influence of growth temperature and growth rate on domain sizes have been investigated in GaInP2 layers. A model has been proposed to rationalize the formation of domains and involves steps present on the surface. Results suggest that ordering like phase separation occurs at the surface while the layers is being deposited. It is inferred that the two microstructural features evolve concomitantly at the surface during layer growth.

We study the impact of improved dopant activation in a BiCMOS SiGe technology, using laser annealing to improve activation, and a low temperature contact module to avoid de-activation. We present the results of simple DC test structure measurements and high frequency bipolar transistor measurements. Improved activation significantly reduces sheet resistance, particularly for polysilicon layers. Likewise, reductions in the bipolar device resistance parasitics cause an improvement in maximum power gain frequency (fMAX).