The Structure of Si and Ge Deposited by Ion Beam Sputtering

Abstract

ABSTRACTThe crystallinity for silicon and germanium films deposited by ion beam sputtering (IBS) as a function of substrate temperatures was determined using Raman spectroscopy, spectroscopic ellipsometry, electrical conductivity and x-ray diffraction measurements. The results show that IBS silicon crystallizes between 300–350°C while germanium crystallizes between 20–200°C. Reasonably good agreement is obtained among the four distinctively different characterization techniques in identifying the onset of crystallinity. A direct relationship is observed between the substrate temperature required for crystallization and the log of the operating pressure for various deposition techniques. Energetic particle stimulation during film growth appears to reduce the crystallization temperature at a given operating pressure. Raman data show that the crystallization temperature depends on the deposition rate. A graded structure is observed in films deposited above 300°C, probably due to oxygen contamination.