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

Abstract

An approach for epitaxial growth of GaP layers on Si substrates at low temperature (380 °C) by plasma-enhanced atomic layer deposition (PEALD) is explored. A significant improvement of the crystalline properties of the GaP layers is obtained using additional in-situ Ar plasma treatment. The epitaxial growth for the first 20–30 nm of GaP on Si is demonstrated from transmission electron microscopy. Moreover, the use of in-situ Ar plasma treatment during the PEALD process allows one to increase the growth rate per cycle from 0.9 ± 0.1 Å/cycle to 1.9 ± 0.1 Å/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.