Theoretical models of Schottky-barrier height formation are reviewed. A particular emphasis is placed on the examination of how these models agree with general physical principles. New concepts on the relationship between interface dipole and chemical bond formation are analyzed, and shown to offer a coherent explanation of a wide range of experimental data.

Recent advances in Schottky barrier concepts

Recent advances in nonsilica fiber technology have prompted the development of suitable materials for devices operating beyond 155 mu m The III-V ternaries and quaternaries (AlGaIn)(AsSb) lattice matched to GaSb seem to be the obvious choice and have turned out to be promising candidates for high speed electronic and long wavelength photonic devices Consequently, there has been tremendous upthrust in research activities of GaSb-based systems As a matter of fact, this compound has proved to be an interesting material for both basic and applied research At present, GaSb technology is in its infancy and considerable research has to be carried out before it can be employed for large scale device fabrication This article presents an up to date comprehensive account of research carried out hitherto It explores in detail the material aspects of GaSb starting from crystal growth in bulk and epitaxial form, post growth material processing to device feasibility An overview of the lattice, electronic, transport, optical and device related properties is presented Some of the current areas of research and development have been critically reviewed and their significance for both understanding the basic physics as well as for device applications are addressed These include the role of defects and impurities on the structural, optical and electrical properties of the material, various techniques employed for surface and bulk defect passivation and their effect on the device characteristics, development of novel device structures, etc Several avenues where further work is required in order to upgrade this III-V compound for optoelectronic devices are listed It is concluded that the present day knowledge in this material system is sufficient to understand the basic properties and what should be more vigorously pursued is their implementation for device fabrication (C) 1997 American Institute of Physics

The physics and technology of gallium antimonide: An emerging optoelectronic material

The frequency dependence of forward capacitance-voltage characteristics of Schottky barrier diodes were investigated by considering the series resistance effect. It is seen that in presence of a series resistance, the capacitance-voltage plot exhibits a peak. The peak value of the capacitance is found to vary with series resistance, interface state density and the frequency of the a.c. signal. The effect of series resistance on the capacitance is found appreciable at higher frequencies when capacitance decreases rapidly with frequency. On the other hand, the conductance of the diode increases with frequency in the high frequency limit. Such a variation in conductance limits the use of well known conductance technique to determine interface state density.

Frequency dependence of forward capacitance-voltage characteristics of Schottky barrier diodes

Semiconducting properties of passive films on stainless steels

Microcontact printing (μCP) has been used to pattern octadecanephosphonic acid on the native oxide surface film of aluminum supported on silicon or on silicon nitride-coated silicon wafers. The patterned alkanephosphonic acid protects the Al2O3/Al film from etching in a solution containing phosphoric, acetic, and nitric acids and water in a ratio of 16:1:1:2 and allows the nonpatterned film to be removed selectively. The patterned Al2O3/Al structures resulting from etching are continuous and electrically conductive within each pattern, and separated patterns are electrically isolated. Resistance measurements of the patterned structures are presented. Using μCP, Schottky diodes of aluminum have been prepared on p-type Si(100). The Schottky diodes exhibit rectifying behavior, and the forward-bias current−voltage (I−V) and reverse-bias capacitance−voltage (C−V) characteristics are presented.

Microcontact Printing of Alkanephosphonic Acids on Aluminum: Pattern Transfer by Wet Chemical Etching

Non-ideal 1 C 2 vs V plots showing curvature concave downwards can be transformed into linear 1 (C − C 0 ) 2 vs V plots by determining the excess capacitance, C0, as the intercept of a C vs (V + V d ) − 1 2 plot, where Vd is the diffusion potential. The corrected curves indicate a uniform doping profile in agreement with independent Van der Pauw measurements. An analysis of the possible significance of C0 indicates that its value can be used as an approximate quality index for materials fabricated by different methods.

Edward Pietras

Papers

Excess capacitance and non-ideal Schottky barriers on GaAs