Growth of epitaxial Si1-xGex layers at 750° C by VLPCVD

Silicon-germanium epitaxial layers have been grown on (100) silicon at 750° C by very low pressure chemical vapor deposition (VLPCVD). Pure SiH₄ and GeH₄ were used as the processing gases. Commensurate films of Si_1-x withx < 0.13 have been deposited up to a critical thickness about 2-4 times larger than the equilibrium value. Interrupted growth, controlled by gas switching, was employed to improve interfacial abruptness. The films have been characterized as a function of SiH₄ and GeH₄ flow rates and germanium content. Growth rate and germanium incorporation as a function of GeH₄:SiH₄ input ratio and total gas flow rate have been studied. We observed that the growth rate of the Si_1-x Ge _x layer decreases as the germanium content in the film or the GeH₄:SiH₄ ratio increases at 750° C using VLPCVD. We also found that, for a given GeH₄:SiH₄ ratio, the germanium incorporated in the solid is independent of the total gas flow rate.