Strain relaxation in PbSnSe and PbSe/PbSnSe layers grown by liquid-phase epitaxy on (100)-oriented silicon

Ternary PbSnSe layers with various Sn contents were grown by LPE on Si(1 0 0) substrates prepared with MBE-grown PbSe/BaF2/CaF2 buffer layers. LPE gro wth initiation temperatures were varied from 380 to 475 degrees C by changi ng the chalcogen concentration in the LPE growth solution. PbSe/PbSnSe doub le layers were also grown using the same procedure. Crack densities and res idual strain values in the epilayers were measured by optical Nomarski micr oscopy and high-resolution X-ray diffraction (HRXRD). Crack densities in Pb 0.91Sn0.09Se layers decreased from 93 to 33 cracks/cm when the growth tempe rature was increased from 430 to 475 degrees C. Crystalline quality, as ind icated by HRXRD FWHM reduction from 522 to 442 arcsec, also improved with t his increase in growth initiation temperature. These results show that IV-V T semiconductor layers grown at higher temperatures are more able to plasti cally deform when subjected to cooling strain caused by thermal expansion m ismatch with the Si substrate. Activation of a strain-relieving higher-orde r dislocation glide mechanism is a likely explanation for this observation. (C) 2000 Elsevier Science B.V. All rights reserved.