Schottky electrical properties

Schottky Diode Growth. The electrical properties of the films deposited using SSP 1 (Fig. 6.13) were evaluated by current versus voltage (I-V) measurements recorded for the thin films using thermally evaporated aluminum contacts (10mm2), to make Schottky barrier diodes (see Fig. 6.14). 

A number of other investigations of the electrical properties of lipid mono- and multilayers were published recently. It is obvious from studies of the conductivity of thin Langmuir films that the electrical properties of metal-organic layer-metal structures can be described by well known concepts from solid state physics, like Schottky injection of electrons from the metal into the lipid film (45, 46, 47). Measurements of dielectric losses in calcium stearate and behenate indicate the presence of movements of dipoles in the organic molecules, and loss peaks connected with the amorphous and crystalline parts of the layers were identified (48). 

In summary we have reviewed the progress in the characterization of electrical properties of ZnO. Improved ohmic and Schottky contacts have been fabricated, the latter suitable for depletion layer spectroscopy. The shallow and deep donor levels have been identified for ZnO from various sources. Further control of deep donors seems necessary for achieving p-conductivity. 

In the literatme, the work function of a metal, p (in eV), is often used to estimate the degree of charge transfer at semiconductor/metal junctions. The work function of a metal is defined as the minimum potential experienced by an electron as it is removed from the metal into a vacuum. The work function ip is often nsed in lieu of the electrochemical potential of a metal, because the electrochemical potential of a metal is difficult to determine experimentally, whereas tp is readily accessible from vacuum photoemission data. Additionally, the original model of semiconductor/metal contacts, advanced by Schottky, utilized differences in work functions, as opposed to differences in electrochemical potentials, to describe the electrical properties of semiconductor/metal interfaces. A more positive work function for a metal (or more rigorously, a more positive Fermi level for a metal) would therefore be expected to produce a greater amount of charge transfer for an n-type semiconductor/metal contact. Therefore, use of metals with a range of tp (or fip.m) values should, in principle, allow control over the electrical properties of semiconductor/metal contacts. 

Konenkamp R. and Rieck 1. (1999), Electrical properties of Schottky diodes on nano-porous TiOi films . Mat. Sci. Eng. B 69-70, 519-521. 

The rectification properties of semiconductor interfaces are the most important electrical characteristic of semiconductor contacts. Certain types of devices, such as transistors, require both ohmic and rectifying contacts on a given semiconductor surface, whereas other devices, such as Schottky barriers, are based on the inherent rectification properties of semiconductor/metal Junctions. Numerous photonic devices, such as photon detectors and photovoltaic cells, require rectification at a semiconductor Junction, and light-emitting diodes require both ohmic contacts and rectifying Junctions in a well-defined geometry. Thus, successful fabrication of a desired device structure depends entirely on the electrical properties of the specific semiconductor contacts that are formed in the process. The principles described above allow the rational fabrication of contacts with the desired properties, and also describe the operation of the resulting devices within a simple, chemically intuitive, kinetic framework. 

The concept of using heteropolyacids in the chemical bath was developed during the 1990s for deposition of CdSe, Sb2S3, CdS, CdTe, etc. The effect of heteropolyacids on the physical, optical, and electrical properties of the films was determined. Their performance in photoelectrochemical, Schottky barrier, and heteroj unchon solar cells has been investigated. 

Recently, the junction properties of Schottky devices using films of chemically synthesised poly(3-cyclohexylthiophene) and poly(3-w-hexylthiophene) units and metals have also been studied [104]. Electrical properties of the poly(3-cyclohexylthiophene)/metal junctions were compared with those of the poly(3-w-hexylthiophene)/metal junctions (Figure 13.11). Better rectification properties of the poly(3-cyclohexylthiophene)/metal junctions were attributed to the decreased conductivity that perhaps results due to steric hindrance in the thiophene ring. 

In the present paper, moreover, in order to clarify also electrical properties of elastomeric conductive polymer, electrical conduction was determined for different content of dispersed conductive particle based on the previous investigation.It was shown that for large particle content, current flows through particles which contact each other and for small particle content, the current passes through the gap between particles by Schottky effect. Therefore, in order to obtain low resistivity, conductive particles should contact each other. 

As a result, in Region 2, the electrical property is dominated by the Schottky effect. 

It is difficult to measure metal/polymer Schottky energy barriers smaller than about 0.5 eV using internal pholoemission. Small Schotiky energy barriers lead to thermal emission currents produced by the absorption of light in the metal which are difficult to separate from true photocurrents 134]. If the structure is cooled to try to improve this contrast, it is often found that the significant decrease in the electrical transport properties of the polymer [27 [ makes it difficult to measure the internal photoemission current. To overcome this limitation, internal photoemission and built-in potential measurements are combined to measure small Schottky energy barriers, as described below. 

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