No abstract

Potentiostatic electrochemical, ellipsometric, and etch‐rate measurements have been made on boron‐ and phosphorus‐doped {100} and {111} silicon wafers in order to study the well‐known etch‐stop phenomenon observed when using orientation‐dependent etching solutions. The current‐voltage curves indicate that as the doping density increases, the separation of the open‐circuit potential and the passivation potential decreases sharply near a doping density of 1019 cm−3. These data indicate that a prepassive monolayer forms at open‐circuit conditions promoted by the high density of dopant impurities. A model for this etch‐stop phenomenon is proposed.

We have synthesized nanoparticles of ZnS doped with Mn for potential use as cathodoluminescent phosphors in field-emission displays (FEDs). We show that the cathodoluminescent efficiency of particles ⩽100 nm in diameter is within 40% of that of a commercial (micron-sized) phosphor when the electron-beam energy ranges between 500 and 3500 eV. The nanoparticles exhibit less current saturation than larger-sized phosphors, an important feature for use in FEDs. Furthermore, the nanoparticles were annealed at just 535 °C, hundreds of degrees below the processing temperatures of standard phosphors. Finally, we discuss the effect of the particle surface on low-voltage luminous efficiency.

Structural and light-emitting properties of nanoparticles of ZnS:Mn annealed in vacuum at temperatures up to 525°C are presented. Annealing the 3.5 nm particles at temperatures up to 350°C caused growth of some particles without substantial change in the luminescence or ZnS lattice. After annealing at 400-525°C, the high-temperature wurtzite phase of ZnS appeared, accompanied by an increase of the average particle diameter to approximately 100 nm and a rearrangement of the Mn ions. Dramatic increase in cathodoluminescence emission was also observed and is compared to the structural information obtained from electron microscopy, x-ray diffraction, x-ray absorption fine structure, and electron paramagnetic resonance measurements.

Orientation-dependent etching of silicon by aqueous KOH is a standard procedure in the microelectronics industry. We have measured the etching products by recording the Raman spectra in real time as the etching of{100} silicon progressed in a 5M KOH solution. The primary etching species has been determined to be OH , and the etching products have been determined to be the silicate SiO2(OH)L Isopropyl alcohol does not appear to participate chemically in the etching process.Aqueous KOH is used as an orientation-dependent etching solution (1) throughout the microelectronics indUstry to make a variety of silicon devices such as V-grooves for VlVIOS transistors (2, 3), pyramids for field-emitter arrays (4), small holes for ink jets (5), and thin-wall Josephson junctions (6). Previously re-