Absorption spectra of LiNbO3 crystals containing ions of the iron group and grown by the Czochralski method have been studied. Observed transitions are compared with transitions between the levels of d2, d3, d4, d5, d6, d7 configurations in the field of cubic symmetry. The magnitudes of the parameters of Coulomb interaction B and C and the parameter of the internal crystal field, Dq, are given, which lead to the best agreement between experimental and theoretical values.

AlxGa1–xN layers up to x = 0.45 are grown on sapphire substrates with different orientations via vapour phase reaction of NH3 with the chlorides of Ga and Al. Epitaxial growth with good crystalline perfection is observed on (0001)‐ and (1102)‐oriented substrates. Indications to the existence of a cubic sphalerite phase in AlxGa1–xN are found. All undoped layers are n‐type conducting with electron concentrations above 1019 cm−3 and show a tendency to lower electron concentrations with rising x. The electron mobility depends strongly on the growth conditions. Optical transmission measurements show the expected increase of the band gap with x. Photoluminescence spectra of undoped layers are dominated by a structure near 3.46 eV independent of x. Some results for Zn‐doped samples are also given.

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The preparation of gallium nitride and aluminium nitride by means of the vapour phase reaction between the corresponding chloride and ammonia i s well known (1 to 3). Increasing attention has been paid to these compounds , especially'to gallium nitride because of their large band gap.Even now the preparation technique of these materials is at a stage of evolution.The search for new possibilities in view of an improvement in the properties of these materials and the examination of a potential application of such material in opto-electronics and other fields of semiconductor technology a r e of considerable interest.One method of prepration of new promising materials is the preparation of solid solutions of gallium nitride and aluminium nitride. The same structure of the nitrides (both compounda crystailize in the wurtzite structure) and the similarity of the lattice constants (GaN a = 3.18 1, c = 5.18 % and AlN a t 3 . 1 1 1 x , c = = 4.980 (4 to 7)) favour the formation of solid solutiom.The apparatus used for the preparation of Gal-xAlxN solid solution6 is similar to that previously developed by us for the epitaxial growth of gallium nitride films with partial modifications. A mixture of the chlorides of gallium and aluminium was introduced into the reaction zone and reacted there with ammonia. 1-x xAs a substrate suitable for the growth of monocrystalline Ga A1 N films sapphire or ruby discs were located in the mixing zone of chlorides and ammonia.Before inserting the substrates into the reaction chamber of fused silica they were chemically polished with a solution of H2SO4 and H PO (1:l) for 10 min followed by washing in acetone. 4The flow rates were 3 to 7 ml/min and 800 ml/min for hydrogen chloride and ammonia, respectively. The total gas flow of nitrogen acting a s carrier gas was

The effect of the dopants Ti, V, Cr. Mn, Ni, Ho, Er, Tm deliberately introduced into the melt of Czochralski grown lithium niobate (LiNbO,) crystals on their electrophysical properties -electric conductivity, dielectric permittivity and loss tangent -has been studied.The characteristics were measured at temperatures up to 1200 "C. The mechanism of dopant introduction into the crystalline lattice and the nature of electric conductivity of LiNbO, at varius temperatures are discussed.Der Einflul3 der Dotierelemente Ti, V, Cr, Mn, Ho, Er, Tm in LiNb0,-Kristallen (nach Czochralski gezogen), deren Schmelze diese Elemente zugesetzt wurden, auf deren elektrophysikalische Eigenschaften -elektrische Leitfahigkeit, Dielektrische Konstante und Verlustwinkel -wurden untersucht. -Die Daten wurden bis 1200 "C gemessen. Der Mechanismus des Eintritts der Dotanten in das Kristallgitter und die Natur der elektrischen Leitung von LiNbO, bei verschiedenen Temperaturen werden diskutiert.