Semiconductor device comprising graded composition SiGe layer

• Main Authors: MAURICE HOWARD FISHER, BENOIT ALFRED LOUIS ROUMIGUIERES, ALED OWEN MORGAN
• Format: Patent
• Language: English
• Published: 17.08.2005
• Edition: 7
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

A semiconductor device comprises a Si substrate 10 and a compound layer 11 of Si1-xGex disposed on the substrate 10. The composition of the layer 11 is varied from x = 0 to x = 0.2 from the substrate 10 to the upper surface of the layer 11, with the rate of change of x increasing through the layer. The rate of change of x may be linear (fig. 3) or non-linear with the distance D through the layer 11. The variation in the composition of the layer 11 is brought about by decreasing the deposition temperature with the distance D through the layer 11. The increasing rate of change of x significantly improves the defectivity levels and the surface roughness at the surface of layer 11.