The study of BP layers and BP/n-Si heterojunctions formed by plasma enhanced chemical deposition on n-Si substrates has been carried out at a temperature of 350 °C using diborane and phosphine. The additional enhancement of hydrogen plasma power was established to make it possible to avoid pinning of the Fermi level at the BP/n-Si interface. Moreover, additional dilution with a hydrogen flow led to an increase in the BP layer conductivity, and the behavior of the current-voltage characteristic of the Au/BP/n-Si structure (golden electrode) became rectifying. Surface states of electrons at the BP/n-Si heterojunctions in all the samples and deep electronic levels with energy 0.58–0.65 eV in BP layers grown without the additional hydrogen flow were detected by admittance spectroscopy.