SiGe films and graded buffers grown by liquid phase epitaxy from different growth solution compositions

SiGe films were grown on Si (0 0 1) by liquid phase epitaxy from short growths (950-940 degrees C) with different solution compositions (2% Ge, 4% Ge, 5% Ge). The initial growth transitions from the characteristic crosshatch morphology into a more three-dimensional morphology with increasing Ge content in the solution. We found that the highest Ge film that maintains two-dimensional film growth is 3.1% Ge. The initial film changes from fully strained to 30% partially relaxed and back to fully strained as the composition increases from 1.4% Ge to 3.1% Ge. In addition, SiGe graded buffers were grown with different solution compositions (2% Ge, 4% Ge, 5% Ge) from 950 to 750 degrees C. The initial film of each graded buffer (the first film to form on the substrate) is fully relaxed at high temperature but experiences tensile strain after cooling to room temperature while the part of the graded buffer further from the substrate experiences increasing compressive strain as the film thickness increases and becomes richer in Ge. The threading dislocation density of graded buffers (i.e. thicker films) grown with the 4% Ge- and 5% Ge-content-solutions is similar to 10(6) cm(-2), one order of magnitude lower than their own initial films (the film grown in the first similar to 10 degrees C growth interval) while the threading dislocation density of the graded buffers grown with 2% Ge-content-solution is similar to its initial film's threading dislocation density, similar to 10(6) cm(-2).