High Pressure Oxidation for Low Temperature Passivation of Si1-xGex Alloys
Thermal passivation of Si1-xGex using high pressure (70 MPa) oxidation was studied for potential use in MOS-device applications. Alloys of CVD-grown Si1-xGex (with x=10 and 15 at. %), 200 and 150-nm thick respectively, were oxidized using high purity dry oxygen at a pressure of 70 MPa and a temperature of 500°C. For comparative purposes, a second set of alloys were oxidized using conventional wet atmospheric pressure oxidation at 800°C. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Transmission electron microscopy (TEM) and MOS C-V measurements were used to characterize the as-grown oxides. Chemical analysis by XPS confirmed that under high pressure conditions, compositionally congruent oxides are grown from these alloys. High resolution TEM and Raman spectroscopy show that the as-grown oxide/semiconductor interface is planar and free of Ge enrichment on a scale of 1–2 monolayers. A midgap interface state density for both the 10 and 15 at. % samples of 1×1012 cm-2eV-1 was estimated based on 1 MHz C-V measurements.
KeywordsRaman Spectroscopy High Resolution Transmission Electron Microscopy High Resolution Transmission Electron Microscopy Image Oxide Fixed Charge High Pressure Oxidation
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