Showing papers on "Amorphous silicon published in 1970"

Switching in elemental amorphous semiconductors

Abstract: Electrical switching phenomenon in amorphous thin films of boron, silicon and germanium is described. The effect of temperature and shelf-life on the threshold and sustaining voltages has been studied. The threshold voltage decreases with increasing temperature while the sustaining voltage is approximately independent of temperature. Both the voltages do not vary significantly with shelf-life. A memory effect is observed in amorphous silicon.

Photoemission from Amorphous Silicon.

Abstract: : Amorphous films were prepared by vapor quenching in ultra-high vacuum. n- and p-type silicon crystals were used as substrates and vapor source. The measurements (performed on clean and cesium covered surfaces) included photoelectric yield, energy distributions of photoelectrons, surface photovoltage, secondary emission with emphasis on elastic reflections, plasmon excitations, and Auger spectra. Information about densities of states, optical transitions, and position of Fermi level was obtained by direct comparison of photoelectric emission from the amorphous film, a silicon crystal, and a metal measured simultaneously. The results were found to depend on the mode of preparation and annealing of disordered films. (Author Modified Abstract)

Hyperfine geometry devices and method for their fabrication

Abstract: A hyperfine geometry device and the method for the making thereof is disclosed which method employs the combination of a patterned oxide layer having apertures designating all the regions to be diffused into a substrate body. A layer of amorphous silicon is formed over the upper surface of the substrate body including the surface of the substrate exposed through the apertures as well as the oxide formed on said upper surface. A third layer of silicon dioxide is formed over the amorphous silicon layer and is patterned to expose selected apertures within the initial or first oxide layer. The patterning of this third layer need not be precise. A diffusion is performed through such exposed amorphous silicon areas into the substrate body. After such diffusion, the amorphous silicon is chemically changed into an oxide for protecting the diffusion aperture from additional diffusions or alternatively, a new passivating layer is formed over such previously diffused areas. In this manner apertures in the first oxide layer are selectively exposed as required in the sequence for manufacturing the desired semiconductor device.

A four-phase moving boundary problem in laser irradiation of amorphous silicon

Abstract: The phase transitions in thin layers of amorphous silicon on the quartz substrate caused by pulsed-laser irradiation are studied as a four-phase moving boundary problem with three moving boundaries using a nonequilibrium thermal model. Three phases, namely the liquid silicon (1-Si), the polycrystalline silicon (pc-Si), and amorphous silicon (a-Si) are treated explicitly, and the fourth phase, Si vapor, is included in the boundary conditions for 1Si. The numerical solution is performed using the Landau transformations, Galerkin finite element method and successive approximation approach with underrelaxation. In a practical application of the numerical model, the XeCl excimer laser irradiation of a- Si layers on quartz substrate is simulated. The effect of the numerical parameters of the model, of the pulse energy density and of the initial thickness of the a-Si layer is discussed.