Fabrication of strain-balanced Si0.73Ge0.27/Si distributed Bragg reflectors on Si substrates

Strain-balanced Si0.73Ge0.27/Si distributed Bragg reflectors (DBRs) which were designed to overcome the limitation of the number of pairs originating from the strain accumulation were fabricated. Raman spectra of Si0.73Ge0.27/Si DBRs with 11 and 25 mirror pairs showed that SiGe and Si layers were under compressive and tensile strain on SiGe virtual substrates as designed. A record reflectivity of 80% was achieved at 1.44 mum in SiGe/Si DBRs with 25 pairs. The surface roughness of the 25 pair sample, however, was increased to about 46 nm compared with 6.3 nm of the 11 pair sample. (C) 2001 American Institute of Physics.