Strained and strain-relaxed epitaxial Ge(1-x)Sn(x) alloys on Si(100) substrates

Epitaxial Ge(1-x)Sn(x) alloys are grown separately on a Ge-buffer/Si(100) substrate and directly on a Si(100)subs trate by molecular beam epitaxy (MBE) at low temperature. In the case of the Ge buffer/Si(100)substrate, a high crystalline quality strained Ge(0.97)Sn(0.03) alloy is grown, with a chi(min) value of 6.7% measured by channeling and random Rutherford backscattering spectrometry (RBS), and a surface root-mean-square (RMS) roughness of 1.568 nm obtained by atomic force microscopy (AFM). In the case of the Si(100)substrate, strain-relaxed Ge(0.97)Sn(0.03) alloys are epitaxially grown at 150 degrees C-300 degrees C, with the degree of strain relaxation being more than 96%. The X-ray diffraction (XRD) and AFM measurements demonstrate that the alloys each have a good crystallin equality and a relatively flat surface. The predominant defects accommodating the large misfit are Lomer edge dislocations at the interface,which are parallel to the interface plane and should not degrade electrical properties and device performance.