STRUCTURAL AND ELECTRICAL-PROPERTIES OF SILICON EPITAXIAL LAYERS GROWN BY LPE AND CVD ON IDENTICAL POLYCRYSTALLINE SUBSTRATES

We compare structural and electrical properties of polycrystalline Si layers grown by chemical vapour deposition (CVD) and liquid-phase epit axy (LPE) on multi crystalline, cast silicon substrates with similar g rain boundary structures. Time-resolved microwave conductivity shows a higher minority carrier lifetime in LPE than in CVD layers; the calcu lated diffusion lengths are up to three times the layer thickness for LPE-grown layers, After etching the samples in Secco or Sirtl solution , we measured in the p-type Si epitaxial LPE and CVD layers practicall y at the same dislocation density as in the same areas of the substrat e. Electron-beam-induced current measurements reveal a low recombinati on strength of grain boundaries and dislocations in the LPE-grown laye rs compared to those of the CVD layers. Transmission electron microsco pe investigations indicate that the lower recombination strength at th e grain boundaries of the LPE layers is due to a lower density of grai n boundary dislocations.