Structural studies of SiGe/Si films grown on Si(001) substrates

Si_0.8Ge_0.2/Si(001) structures were grown at various growth temperatures (250 ∼ 760°C) using molecular beam epitaxy (MBE) and solid phase epitaxy (SPE). The variation of the strain and the microstructure of film were investigated using double-crystal X-ray diffractometry, Rutherford backscattering spectroscopy, and transmission electron microscopy. For the samples grown below 350°C using MBE, an amorphous SiGe film developed over the SiGe single crystalline layer with a jagged amorphous(a-)/crystalline(c-) interface, and many defects, such as stacking faults and microwins, were formed below the a/c interface. SiGe films with good single crystallinity were obtained from the samples grown at 440 ∼ 660°C using MBE. Dislocations developed in the single crystal SiGe film for the samples grown above 680°C. However, for the sample annealed at 550°C using the SPE method, the SiGe film was found to be amorphous, and a single crystalline SiGe film with defects was formed in the sample annealed 650°C.