Plasma Enhanced Atomic Layer Deposition of InP Layers and Multilayer InP/GaP Structures on Si Substrate

Abstract

For the first time, InP layers were grown on Si substrates at a temperature of 380°C using the plasma-enhanced atomic layer deposition. According to X-ray diffraction analysis and transmission electron microscopy, the layers are microcrystalline with a grain size of 20–30 nm and a preferred orientation (111). Raman spectra exhibit clearly distinguish the LO peak at 341.9 cm^–1, which is characteristic of crystalline InP. Microcrystalline InP layers grown on fused silica substrates demonstrated a high photoconductivity of 2.3 Ω^–1 cm^–1 under solar spectrum AM1.5G (100 mW/cm²) illumination. The study of the growth of layers of binary compounds InP and GaP in one process of plasma-enhanced atomic layer deposition demonstrated the fundamental possibility of controlling the composition of InP/GaP digital alloy. The InP/GaP digital alloys are characterized by the coalescence of the LO peaks of InP (341.9 cm^–1) and GaP (365 cm^–1) in the Raman spectra. Increase of GaP component in the layer leads to boarding of this feature in the Raman spectra due to a shift of the edge towards the GaP peak (402 cm^–1). A study of the optical properties by transmission and reflection measurements of microcrystalline InP/GaP digital alloy layers deposited on transparent substrates demonstrated the possibility of varying the optical gap in the range of 1.3–2 eV.