Intrinsically dopant ions

LaMn03 is an intrinsic p-type conductor. Electronic conductivity is enhanced by substitution of the La3+ site with divalent ions such as strontium or calcium. Of the alkaline-earth dopants, Sr substitution is preferred for SOLC applications because the resultant perovskite forms stable compounds with high conductivity in the oxidizing atmosphere found at the cathode [41], Extensive data show that La, xSi. MnO where x = 0.1 - 0.2, provides high conductivity while maintaining mechanical and chemical stability with YSZ [41, 42],... 

In ion implantation the gaseous dopant is ionized and accelerated into the wafer. SIMS has been used extensively to obtain dopant concentration depth profiles because it is the most sensitive of the surface analytical techniques and because sputtering is an intrinsic part of the dynamic SIMS process (40). AES, combined with ion sputtering, has also been used to obtain depth profiles for high dose implants (41). 

In a second embodiment the strip detectors A to H are mounted on an intrinsic p-type silicon substrate 3A covered by a silicon oxide layer 3B. A patterned arrangement of conductor tracks 21 is formed in the semiconductor base 3B. Each track is formed by diffusion or ion-implantation of an n-type dopant material, and isolated from adjacent tracks by means of a channel stop network 23. Bridging links of nichrome-gold are formed to define and connect the read-out regions to the tracks 21. The links 25 are paired and thus provide voltage detection contacts. The tracks 21 are connected to connection pads 29. Signal processing circuitry is incorporated in the semiconductor base layer 3B. 

Point defects are an important part of the work in this paper. There are many reasons for the formation of point defects in minerals and their presence can exert important perturbations on the properties of the material (4). Point defects are formed because of the thermally driven intrinsic disorder in a lattice, the addition of aliovalent impurities or dopants, the presence of metal-nonmetal nonstoichiometry, and the creation of nonideal cation ratios. The first three source of defects are well-known from binary compounds but the last is unique to ternary compounds. Ternary compounds are much more complex than the binary compounds but they also have gained a great deal of attention because of the variety of important behavior they exhibit including now the presence of superconductivity at high temperatures. The point defects can be measured by introducing probe ions into the lattice. 

The effects of deliberately added donors, such as titanium, and acceptors, such as iron and magnesium, on electrical conductivity have been studied. Doping with aliovalent ions affects the concentration of intrinsic defects and, in consequence, the diffusivity of A1 and O. In the case of variable-valency dopants, changes in p0l change the fraction of dopants in the aliovalent state and the nature and concentration of the defects. For example, the dopant Ti substitutes for A1 and, in the fully oxidized state, produces the defect TiA1, compensated by Va", so that... 

Even if unwanted chemical transformations of doped conjugated materials can be avoided by strict exclusion of air, the long-term stability is limited by a de-mixing of dopant and redox system. An alternative approach to persistent electrical conductors is therefore concerned with the synthesis of intrinsic conductors. Toward that end the lowering of the band gap is desirable which, on the other hand, is known to reduce the chemical stability. The synthetic approaches taken must therefore focus on a compromise between electronically attractive 7i-structure, stability and processability of the material. In conclusion, it is the flexible combination of different areas of research which provides new insights into the properties of monomeric, oligomeric and polymeric radical ions. 

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