Semiconductive compounds electrical properties

Novel substituted jr-electron-donor tetrathiaful-valenes are described in connection with the synthesis of dendrimeric molecules with electrically conducting or semiconducting properties.151 Compounds such as 110 (Scheme 49) show two one-electron... 

It has been shown in Section 1.3.7 that in semiconductors or insulators the lattice defects and electronic defects (electrons and holes), derived from non-stoichiometry, can be regarded as chemical species, and that the creation of non-stoichiometry can be treated as a chemical reaction to which the law of mass action can be applied. This method was demonstrated for Nii O, Zr Cai Oiand Cuz- O in Sections 1.4.5, 1.4.6, and 1.4.9, as typical examples. We shall now introduce a general method based on the above-mentioned principle after Kroger, and then discuss the impurity effect on the electrical properties of PbS as an example. This method is very useful in investigating the relation between non-stoichiometry and electrical properties of semiconductive compounds. 

Thus, it has been shown that the electrical properties of semiconductive compounds depend on the chemical composition, viz. non-stoichiometry, and therefore the control of the composition is indispensable in the control of the semiconductive properties of the compounds. 

Semiconductive elements Si and Ge (Group IVB or 13 in the periodic table) have become very important electronic materials since development of a purification method. The electronic properties of semiconductive elements of high purity can be controlled by the species and concentration of defects and impurity elements. On the other hand, in the case of semiconductive compounds, that is, III-V and II-VI compounds, we have to consider not only control of the purity of constituent elements but also the nonstoichiometry, both of which have much influence on the electronic properties. In this sense, control of the electrical properties of semiconductive compounds is more difficult than that of semiconductive elements. 

The theory outlined above was developed for group IY semiconducting elements such as silicon and germanium some of the compounds of group III and Y elements, the III-V compounds, are also covalently bonded and have similar electrical properties which can be described in terms of a band model. The best known semiconducting III-V compound is GaAs, which is exploited for both its photonic and semiconducting properties. 

The heat of atomization is an important parameter which is a measure of the chemical bondii in a semiconducting compound and is well correlated with the electrical and the thermochemical properties [2, 3, 23]. The heat of atomization is the sum of the enthalpy of... 

Metallophthalocyanines and -naphthalocyanines have be used recently for the preparation of materials, which exhibit interesting semiconducting and nonlinear optical properties (1). In this report we concentrate on the electrical properties of phthalocyaninato and naphthalocyaninato transition metal compounds. A necessary condition for achieving good electrical conductivities in... 

A comprehensive report which focussed on the La2 xSrxCu O4-x/2+S ser es was published (139) in 1983 by this research group. In this broad review they reported the magnetic and electrical transport properties of these mixed-valent copper oxides in the temperature range 120-650 K. They concluded that the original semiconducting behavior in La2Cu04 transformed to semi-metallic behavior as the Cu3+ content increased with Sr-substitution. No experiments were conducted below 50 K, and therefore superconductivity was not observed. Three series of compounds, with 0.00 < x < 1.20 were... 

Attempts have recently been made to produce organic semiconductor components for industrial use without taking account of the characteristic parameters of semiconductivity of organic compounds. Nowadays, we know the need for a systematic study of these parameters because they can show us both the limits of application and the conditions which must be fulfilled for maximum use of the electrical and photoelectrical properties of dyes and other organic compounds. 

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