In quantum-confinement SiGe layers of second type Si/Si j^GeySi heterostructures, electron-hole liquid (EHL) was observed and investigated by low-temperature photoluminescence spectroscopy in the near infrared and visible spectral regions. It has been found that the EHL consists of quasi-two-dimensional holes in the quantum well in the SiGe-layer and quasi-three-dimensional electrons, also located in this layer. The emission lines of biexcitons were observed in the luminescence spectra of these structures at relatively low levels of pumping. It has been found that the binding energy of biexcitons in the quasi-two-dimensional layers is considerably larger than that in the bulk silicon.