Low temperature epitaxial growth of GaP on Si by atomic-layer deposition with plasma activation

An approach for epitaxial growth of GaP layers on Si substrates at low temperature (380 degrees C) by plasma-enhanced atomic layer deposition (PEALD) is explored. A significant improvement of the crystalline properties of the GaP layers is obtained using additionalin-situAr plasma treatment. The epitaxial growth for the first 20-30 nm of GaP on Si is demonstrated from transmission electron microscopy. Moreover, the use ofin-situAr plasma treatment during the PEALD process allows one to increase the growth rate per cycle from 0.9 +/- 0.1 angstrom/cycle to 1.9 +/- 0.1 angstrom/cycle and reduce the RMS roughness from 3.76 nm to 1.88 nm. The effect of Ar plasma treatment on the electronic properties of the GaP/Si interface is studied by deep level transient spectroscopy (DLTS). A defect level at (0.33 +/- 0.03) eV below the conduction band is observed in the subsurface layer of Si for the GaP/Si structure grown under Ar plasma treatment. However, the defect response observed by DLTS vanishes after rapid thermal annealing at 500 oC in nitrogen ambient.