Si(100) wafers were prepared by both diamond turning and standard lapping and polishing techniques. For single-point diamond machining, characterization of subsurface damage resulting from ductile-regime machining identified a plastic-yield zone consisting of slip planes and dislocation networks extending 1 to 3 μm deep despite surface root-mean-square roughness values as low as 5 nm. For conventional lapping and polishing using alumina grit, a transition from brittle to ductile yield was observed for grit sizes less than 300 nm. Subsurface damage depth correlated to surface roughness in a more straightforward manner than for the diamond point machining. Completely damage-free material removal was obtained only when a chemical component to the polishing was present.

Articles you may be interested inComparison of two surface preparations used in the homoepitaxial growth of silicon films by plasma enhanced chemical vapor deposition J. Vac. Sci. Technol. B 21, 970 (2003); 10.1116/1.1568352Low-temperature Si epitaxial growth on oxide patterned wafers by ultrahigh vacuum electron cyclotron resonance chemical vapor deposition

Atomic wafer fusion of GaSb to GaAs, and the transfer of epitaxial GaSb/GaInAsSb/GaSb heterostructures to GaAs by fusion and substrate removal are demonstrated for the first time. Wafers and epilayers were fused with or without application of mechanical pressure at temperatures as low as 350 °C. A periodic pattern of grooves etched into the GaAs wafer and an overpressure of As and Sb vapor were used to improve covalent bonding. Varying degrees of mass transport and covalent bond formation between wafers were observed in cleaved crosssections under high-resolution scanning electron microscopy. Epilayers fused without pressure application exhibited significantly better structural and optical properties compared to those fused with pressure.

Nanocrystalline silicon aggregates imbedded in a predominantly amorphous silicon layer have been observed in anodically etched p-Si(100) by using valence band x-ray photoelectron spectroscopy and lattice imaged high-resolution transmission electron microscopy (XTEM). XTEM has identified the as-prepared porous silicon to be a mixed phase of amorphous and nanocrystalline silicon, with the nanocrystalline aggregates being randomly dispersed throughout the full thickness of a 1 μm thick amorphous layer and exhibiting a size distribution from 2 to 5 nm in diameter. The abundance of the nanocrystalline aggregates seems to decrease as the anodic etching proceeds and as the sample is irradiated by x rays at room temperature in ultrahigh vacuum. Valence band photoelectron measurements show evidence for a crystalline-to-amorphous phase transition induced by x radiation which may, in part, be activated by photoelectron stimulated hydrogen desorption. The x-ray irradiated samples also exhibit a significant reduction in photoluminescence yield, possibly caused by a reduction in the density of nanocrystallites. The observed mixed phase porous silicon and the metastability of the nanocrystallites help to explain apparent contradictory descriptions of the nature of porous silicon.