Properties of diamond structure SnGe films grown by molecular beam epitaxy

Using molecular beam epitaxy, we have successfully grown thin films of Ge1-xSnx on silicon (100) substrates. These films have been analyzed structurally by Auger Electron Spectroscopy, X-ray Diffraction, and Rutherford Backscattering. The electrical and optical properties have been investigated by Hall effect and IR absorption spectroscopy. During the initial stages of growth, the tin accumulates on the surface. As the growth proceeds, tin from this accumulated reservoir begins to incorporate until steady state growth is achieved. Increased optical absorption is observed at long wavelengths in higher tin content alloys, and the magnitudes suggest that it is from the direct gap of the semiconductor. On exposure to air a thin oxide layer is formed. The films are found to be unstable above 190°C. © 1990.