A.N. Daw

Bio: A.N. Daw is an academic researcher from University of Calcutta. The author has contributed to research in topics: Silicon & Transistor. The author has an hindex of 6, co-authored 21 publications receiving 87 citations.

Characteristics of metal-semiconductor contacts fabricated by the electroless deposition method

Abstract: Metal-semiconductor contacts have been fabricated by electroless deposition of Cu on chemically cleaned n -type silicon and their characteristics studied. The values of barrier height and the ideality factor are found to be comparable to those of vacuum evaporated contacts. A non-linearity in the 1/ C 2 vs V plot has been observed and the same has been satisfactorily explained by taking surface state capacitance into consideration.

On the variation of cut-off frequency with emitter end concentration of a diffused base transistor

Abstract: The effect of mobility degradation at high impurity concentrations on the cut-off frequency of a diffused base transistor with exponential impurity profile in the base has been considered analytically. It has been shown that the cut-off frequency exhibits a maximum with increase in emitter and concentration. The results are compared with those of complementary error function and Gaussian base impurity profiles.

On the Lifetime and Diffusion Constant of the Injected Carriers and the Emitter Efficiency of a Junction Transistor

Abstract: Values of the effective lifetime and of the apparent diffusion constant of the minority carriers in the base region of p-n-p alloy junction transistors of three different types have been determined. It is found that for a given temperature the effective lifetime passes through a maximum as the bias current is increased from a, low value. This is explained on the basis of the relative contributions to the lifetime of volume and surface recombination, The analysis also yields separately the values of the volume and the surface recombination lifetimes. Both the lifetimes are found to decrease with decreasing temperature. Further, the volume recombination lifetime is found to be appreciably smaller than those observed in n-typo germanium in bulk. The true values of the diffusion constants, as determined from the measured apparent values, arc found to obey an empirical relation that closely agrees with the relation for bulk germanium semi-conductor of the same type. A method of estimating the emitter ...

Plasma etching: Yesterday, today, and tomorrow

Abstract: The field of plasma etching is reviewed. Plasma etching, a revolutionary extension of the technique of physical sputtering, was introduced to integrated circuit manufacturing as early as the mid 1960s and more widely in the early 1970s, in an effort to reduce liquid waste disposal in manufacturing and achieve selectivities that were difficult to obtain with wet chemistry. Quickly, the ability to anisotropically etch silicon, aluminum, and silicon dioxide in plasmas became the breakthrough that allowed the features in integrated circuits to continue to shrink over the next 40 years. Some of this early history is reviewed, and a discussion of the evolution in plasma reactor design is included. Some basic principles related to plasma etching such as evaporation rates and Langmuir–Hinshelwood adsorption are introduced. Etching mechanisms of selected materials, silicon, silicon dioxide, and low dielectric-constant materials are discussed in detail. A detailed treatment is presented of applications in current silicon integrated circuit fabrication. Finally, some predictions are offered for future needs and advances in plasma etching for silicon and nonsilicon-based devices.

On the current transport mechanism in a metal—insulator—semiconductor (MIS) diode

Abstract: The current transport mechanism in an MIS-tunnel diode has been studied by considering both the process of tunneling and the effect of pinholes in the insulating layer. It has been shown that in order to explain the experimental J - V characteristics of MIS-diodes, presence of a thin interfacial layer of thickness δ p within the pinholes should be considered. From an analysis of the tJ - V and C - V characteristics, a method has been suggested for the estimation of the value of δ p . The values of interface trap density and barrier height for the MOS-part of the diodes are also calculated. The dependence of barrier height on oxide thickness for the diodes is found to obey the barrier height model of Cowley and Sze.

Superconductor‐normal‐superconductor microbridges: Fabrication, electrical behavior, and modeling

Abstract: Josephson‐effect devices consisting of two superconducting thin films coupled by a short nonsuperconducting metallic bridge are investigated in this work. To fabricate these devices we have developed processing techniques which are compatible with refractory superconductors and show promise for the high‐Tc A15 materials as well. We describe in detail the electrical behavior of Nb‐Au‐Nb and Nb‐Cu‐Nb bridges, which have been made with resistances up to 0.4 Ω and critical current‐resistance (i.e., IcRn ) products as high as 0.5 mV. We have modified the usual theoretical model for the critical current in order to account for the actual geometry of our devices thereby obtaining semiquantitative agreement with experiment. A single parameter is used in this analysis to characterize the proximity effect and we find that values inferred from the critical currents of bridges agree well with those inferred from the behavior of the transition temperature of S/N bilayers. Typical current‐voltage characteristics are in good agreement with the predictions of the time‐dependent Ginzburg‐Landau model with rigid boundary conditions. At high dissipations heating is observed and explained by a generalized version of the hotspot model. Finally, we have employed the models for superconductor‐normal‐superconductor microbridge behavior to evaluate the ultimate potential of this particular weak‐link configuration for practical applications.