STRUCTURAL AND OPTICAL CHARACTERIZATION OF UNDOPED SI-SI0.78GE0.22 SI(001) SUPERLATTICES GROWN BY MBE/

We report the results of structural characterisation of five-period Si -Si1-xGex/Si(001), (x = 0.22) strained-layer superlattices (SL) by SIM S with an ultra-low energy (500 eV) O-2(+) primary beam and by 1.0 MeV He-4(+) RBS together with optical and Raman spectroscopies. The SLs w ere grown by solid source MBE in a VG Semicon V90S machine at five dif ferent substrate temperatures in the range 550 degrees C < T-s < 810 d egrees C, which corresponds to the 'equilibrium regime' of Ge segregat ion near the Si/SiGe interface. The results obtained give information on material and interface quality, layer thicknesses, and state of the strain in the heterostructure. A good agreement is shown between all characterisation methods used. (C) 1997 Elsevier Science S.A.