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Electrode-oxide semiconductor interfaces

The physical understanding of the electrode-oxide semiconductor interfaces are described in this section. Interfaces of this type occur in oxide semiconductor gas sensors and metal-insulator-semiconductors (MIS) devices. When a metal is contacted with oxide, the potential barrier arises from the separation of changes of the metal-oxide interface as well as the metal-semiconductor contacts. [Pg.80]

The first significant step towards understanding the mechanism of the electrode-oxide semiconductor is given in an ideal case contact. Another advance in our understanding of the electrode-oxide semiconductor junction is concerned with contacts with surface states, and interfacial layer and [Pg.80]

11 Energy-band diagram of metal contact to n-type semiconductor with (a) neutral materials separated from each other, and [Pg.81]

The above description applies only to an n-type semiconductor whose work function is less than the metal work function ,. The electron energy-band diagrams for an n-type semiconductor with are shown in Fig. 3.12. [Pg.83]

The foregoing discussion has shown that, in case of an n-type semiconductor, a metal-semiconductor contact is rectifying if Oj and is nonrectifying if Oj. The opposite is true for a metal p-type semiconductor contact. The work functions of various metals and semiconductors are given in Table 3.1.  [Pg.83]


Charge carrier transport in the electrode-oxide semiconductor interfaces... [Pg.89]

The aim of this chapter is to describe and review the interface chemistry and transition theory of the electrode-oxide semiconductor layer in gas sensor operation. Section 3.2 deals with criteria for selecting the metal and semiconductor materials used in the fabrication of gas sensors.The chemistry and... [Pg.64]

Any charge change occurring only between the reference electrode and the semiconductor is a candidate for a change of Ids. In particular one of the most important points is the surface potential at the oxide-solution interface (surface potentials between the CIM and the solution and the potential between the SiC>2 and the CIM, in the presence of a given CIM. The ISFET operation may be represented by the following changes-flow which may be considered as superimposed on the quiescent point determined by the reference electrode potential ... [Pg.81]

Direct measurement of the change in interfacial potential difference at the oxide-electrolyte interface with change in pH of solution can be measured with semiconductor or semiconductor-oxide electrodes. These measurements have shown d V g/d log a + approaching 59 mV for TiC (36, 37). These values are inconsistent with the highly sub-Nernstian values predicted from the models with small values of K. (Similar studies 138.391 have been performed with other oxides of geochemical interest. Oxides of aluminum have yielded a value of d t)>q/A log aH+ greater than 50 mV, while some oxides of silicon have yielded lower values.)... [Pg.74]

It is, of course, well known that metal-semiconductor interfaces frequently have rectifier characteristics. It is significant, however, that this characteristic has been confirmed specifically for systems that have been used as inverse supported catalysts, including the system NiO on Ag described above as catalyst for CO-oxidation. In the experimental approach taken, nickel was evaporated onto a silver electrode and then oxidized in oxygen. A space charge-free counter-electrode was then evaporated onto the nickel oxide layer, and the resulting sandwich structure was annealed. The electrical characteristic of this structure is represented in Fig. 8. The abscissa (U) is the applied potential the ordi-... [Pg.19]

At oxide semiconductor electrode-electrolyte interfaces, with no contribution from surface states, the electrical potential drop exhibits three components the potential drop across the space-charge region, sc, across the Helmholtz layer, diffuse double layer, d, the latter becoming negligible in concentrated electrolytes... [Pg.250]

As = surface area of a semiconductor contact [A ] = concentration of the reduced form of a redox couple in solution [A] = concentration of the oxidized form of a redox couple in solution A" = effective Richardson constant (A/A ) = electrochemical potential of a solution cb = energy of the conduction band edge Ep = Fermi level EF,m = Fermi level of a metal f,sc = Fermi level of a semiconductor SjA/A") = redox potential of a solution ° (A/A ) = formal redox potential of a solution = electric field max = maximum electric field at a semiconductor interface e = number of electrons transferred per molecule oxidized or reduced F = Faraday constant / = current /o = exchange current k = Boltzmann constant = intrinsic rate constant for electron transfer at a semiconductor/liquid interface k = forward electron transfer rate constant = reverse electron transfer rate constant = concentration of donor atoms in an n-type semiconductor NHE = normal hydrogen electrode n = electron concentration b = electron concentration in the bulk of a semiconductor ... [Pg.4341]

Also, although Eqs. (1.69) and (1.70) resemble those for a Sehottky barrier, there are several important differences in the physical and chemical details (1) charge transfer between a semiconductor and a solution is a slow process, whereas that between a metal and a semiconductor is fast (2) the diffusion of redox speeies in the solution toward the electrode surface is slow whereas that of charge carriers in metal is fast (3) the reduced and oxidized species of the redox couple as donors and acceptors can change independently whereas the occupied and unoccupied states of the metal cannot be changed artificially (4) a Helmholtz layer is present between the semiconductor electrode and the solution whereas no such layer exists at the metal/semiconductor interface. [Pg.26]

What follows is intended as a review of our own work, which is a small part of a rapidly growing area of chemistry. Note, for example, reference 1. Our emphasis has been on redox events at chemically fabricated metal and semiconductor interfaces. Given the chemical sites used and the configuration of the resulting structures, the presence of the electrode automatically provides a method of analysis and a means for monitoring interfacial events. The electrode also serves as a controlled potential source of oxidizing or reducing equivalents for the interface. [Pg.134]

The photoelectrochemical process can be divided into the four reactions (Equations 1-4) involving photon excitation and charge separation in the Pc film (Equation 1) recombination events (Equation 2), charge transfer at the electrode substrate-Pc. interface (Equation 3) and charge transfer at the Pc-solution interface (Equation 4). The net process is the oxidation of hydroquinone with 0 to form quinone and R. If this is normally a thermodynamically uphill process where the dye is superimposed on a semiconductor substrate, then true photosensitized energy conversion has occurred. [Pg.215]

Around 1975, investigations of photoelectrochemical reactions at semiconductor electrodes were begun in many research groups, with respect to their application in solar energy conversion systems (for details see Chapter 11). In this context, various scientists have also studied the problem of catalysing redox reactions, for instance, in order to reduce surface recombination and corrosion processes. Mostly noble metals, such as Pt, Pd, Ru and Rh, or metal oxides (RUO2) have been deposited as possible catalysts on the semiconductor surface. This technique has been particularly applied in the case of suspensions or colloidal solutions of semiconductor particles [101]. However, it is rather difficult to prove a real catalytic property, because a deposition of a metal layer leads usually to the formation of a rectifying Schottky junction at the metal-semiconductor interface (compare with Chapter 2), as will be discussed below in more... [Pg.236]


See other pages where Electrode-oxide semiconductor interfaces is mentioned: [Pg.65]    [Pg.80]    [Pg.103]    [Pg.65]    [Pg.80]    [Pg.103]    [Pg.28]    [Pg.371]    [Pg.249]    [Pg.569]    [Pg.472]    [Pg.231]    [Pg.233]    [Pg.239]    [Pg.301]    [Pg.74]    [Pg.429]    [Pg.438]    [Pg.276]    [Pg.219]    [Pg.371]    [Pg.870]    [Pg.876]    [Pg.423]    [Pg.88]    [Pg.179]    [Pg.245]    [Pg.214]    [Pg.258]    [Pg.259]    [Pg.259]    [Pg.2695]    [Pg.77]    [Pg.472]    [Pg.489]    [Pg.205]   


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Electrode interface

Oxidation electrode

Oxide semiconductors

Semiconductor electrode interface

Semiconductor electrodes

Semiconductor interfaces

Semiconductor oxidic

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