Vacuum
Generally, the outgassing rate of any solid drops down smoothly with increasing time, according to the existing theories on outgassing. This behaviour is caused by the reduction of the gas concentration in the bulk, or by the reduction of the gas coverage on the surface as a consequence of the outgassing process. Some publications, however, report on constant outgassing rates, which were observed...
The early stages of the growth of Cu layers deposited on Ag(110) and of Ag layers on Cu(110) have been studied by Total Current Spectroscopy, in conjunction with AES and ΔΦ measurements. The results are discussed in terms of structural properties of the substrate and the adsorbate layer. Information on the growth types, lattice relaxation and inner potential are extracted from experimental data.
The PdCu(110) single crystal alloy surfaces (bulk Pd/Cu = 1:1) were prepared by sputtering and annealing at different temperatures. Surfaces with Cu/Pd contents ranging from ~ 100% Pd to ~ 100% Cu at the top surface layer could be obtained. AES with surface region (SR) analysis of ~ 4 layers, LEED and TDS of CO with top surface layer (TL) analysis were the methods used for characterization. LEED of...
A direct method to calculate the pumping speeds of sputter ion pumps is proposed. The pumping speed is obtained by calculating the electron density trapped in a Penning cell and the corresponding ion current numerically. Empirical coefficients or terms applied in conventional formulae for pumping speeds are not used. Conversely, the parameters sticking probability and sputtering yield are introduced,...
Erbium films of 250-700 nm thickness were deposited on Mo substrates of different roughness, at different substrate temperatures, for deposition rates of 0.5 nms - 1 and 7.65 nms - 1 under three different uhv conditions, namely standard, semi-rigorous and rigorous. Microstructures of these films were obtained by SEM, while the grain sizes were measured using an image analyser...
The design, construction, and performance of a simple substrate heater capable of operating at temperatures above 800 o C, either in vacuum or in oxygen, is described. The heater uses halogen projector bulbs and has been employed in the deposition of YBCO superconducting thin films by sputtering and pulsed laser deposition. Performance data are given for heating times and bulb life.
The operation characteristics of some axial-emission gauges similar to the construction of Chen and Suen were studied in the high vacuum range. Electron space charge effects arose in the case of high cathode potentials, yielding a strong dependence of the sensitivity on the emission current. To avoid this dependence it is necessary to operate the gauge with low cathode potentials or to increase the...
Ion kinetic investigations are performed on a 27.12 MHz capacitively coupled parallel plate discharge configuration using argon and oxygen as the process gases. The incident ions on the grounded electrode are separated, according to their mass and energy, and the influence of rf-power density and total pressure on the ion mass spectra and, especially, on the ion energy distribution are discussed....
Of use in the optoelectronic field, CdTe has been prepared by vapour transport and electrodeposition processes and after a brief review of reported work an account is given of a study of the structural and electrical properties of CdTe films prepared by electrodeposition. The effect of the defect states on the carrier transport in CdTe films has been discussed critically by studying the space charge...
State of the art developments in silicon process and device technology other than VLSI are described and illustrated with reference to current work in the Northern Ireland Semiconductor Research Centre (NISRC). Applications discussed include power electronics and SMART power, fast bipolar heterojunction devices, large area electronics and sensors and actuators. Some of the specialised techniques used...
We have measured the CVV Auger spectra of Fe and S from FeS 2 and compared them, after deconvoluting, with results from other techniques and with band structure calculations. These Auger spectra exhibit a number of interesting features, including a strong feature similar to that found in metallic Fe, previously assigned to an 'autoionisation' process. The effective hole-hole interaction energy...
Voltage controlled negative differential resistance (NDR), electron emission (EE) and electroluminescence (EL) have been extensively studied for electroformed thin gold films deposited on glass substrates. The physical stability and the electrical significance of gold islands within the small, 1 μm, gap are not understood. The effect of treating the glass substrate with (3-Mercaptopropyl)trimethoxysilane...
Hydrogen depth profiles in the surface region of the metals Au, Ag, Cu and some characteristics are studied by ERDA. The structures of hydrogen depth distributions in these metal surfaces are similar, a layer of surface adsorption, diffusion depth and a hydrogen-containing matrix are obvious and some of the differences between them are discussed. The results show that the method is valuable for the...
The aim of this paper is the investigation of a GeSi/Si heterostructure formation obtained by deposition of Ge and Si layers of different thickness. Ge x Si 1 - x /Si films obtained by MBE in high vacuum were multilayered systems with alternate Si and Ge layers. The layer thickness was 10-150 a. The samples were obtained at substrate temperatures from RT to 700 o C...
This paper presents an exhaustive review of trends in the development of methods for calibration of vacuum gauges in which pressure-time dependences are used. The author proposes and describes techniques for improving the calibration, the main objective of which is to extend the range of pressure measurements, to increase their accuracy and to raise the productivity of calibration (by reducing the...
The stoichiometry of a-SiN x :H films is determined by conventional elastic recoil detection analysis (ERDA) using 90 MeV i 5 8 Ni ions. Hydrogen depth profiling indicated that the non-uniformity in H concentration across the film thickness is about 12%. The present experiment indicated the capability of conventional ERDA for simultaneous multi-element detection in a thin film...
A new technique to determine the optical constants and band gaps of a bilayer semiconductor film is described. The theory and the technique have been successfully applied to determine the optical parameters of individual layers for three bilayered semiconductor systems: CdS/CdTe, CdS/CuInSe 2 and ZnS/ZnSe.
Microscopic contaminants occurring in the semiconductor manufacturing environment have been analysed using SAXPS. The molecular information obtained can be utilised to successfully identify and locate the sources of contamination. A description of the working principles of SAXPS and case studies in wafer fabrication and packaging assembly are presented.
The angular distribution of sputtered atoms and the surface topography of cadmium bombarded by 27 KeV Ar + ions were studied using Rutherford Backscattering Spectroscopy (RBS) and Scanning Electron Microscopy (SEM) analysis. It is shown that the variation of both distribution shapes and topographic features is found to be sensitive to the dose of incident ions and the relationship between...