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The phenomenon known as the spectral photoelastic effect (SPE) is discussed and explained. A remote optical pressure sensor has been constructed based on the SPE. A measurement system using this sensor is described. The relative uncertainty obtained is about 10-2 or better, and depends on the qualities of the electronic and optical parts of the system, the calibration process and the calculation algorithm.

Nanocrystalline layers of C3N4, BN, AlN and GaN were grown by Impulse Plasma Assisted Chemical Vapor Deposition method on silicon substrates kept at 300K. Optical absorption studies of the layers revealed broad bands below the fundamental absorption edge, which were ascribed to transitions involving defect levels. When excited by a 3 mW He-Cd laser (325 nm line) all samples showed a wide photoluminescence spectrum (2.0 to 3.5 eV), but the disordered crystalline structure quenched the excitonic photoluminescence observed in monocrystals. The efficient visible luminescence of nanocrystalline AlN layers in the 2–3 eV region observed under non optimal excitation conditions (energy bandgap of AlN is twice the excitation energy) is promising for optoelectronic use of this material as a visible light source.

In this work, results of photoluminescence and absorption measurements on pulse plasma assisted CVD layers of AlN are presented. We studied nanocrystalline layers grown on silicon substrate at a temperature of 300 K. The efficient photoluminescence of nanocrystalline AlN layers, obtained under non optimal conditions, i.e. relatively low excitation energy, seems to be promising for light emitting applications of this material.

This paper discusses phase composition as well as electrical and optical properties of carbon-nitrogen (CN) compound obtained by reactive pulse plasma method. It is shown that material produced in such a way is a mixture of an amorphous compound which we have called polycyanoimine and nanocrystalline diamond. Its electrical and optical properties differ from those of DLC obtained by the same method. During electrical measurements there have not been observed diode-like current-voltage (I-V) characteristics, what rules out the possibility that nitrogen atoms might act as a dopant in obtained material. It has been found that electrical resistivity of investigated films, as ranging from 109 to 1011 Ωcm, has been higher than that of DLC layers produced from pulse plasma. However, subsequent low temperature (350 °C) annealing has resulted in the drop of their resistivity to the value of 106–107 Ωcm, the same as for DLC materials. Annealing has also influenced refractive index of investigated layers resulting in its increase from 1.9 to 2.13. Moreover, it has been observed that CN layers produced under the highest nitrogen pressure (i.e. 60 Pa) have been luminescent when illuminated with 514.5 nm laser beam, which does not occur in the case of DLC.

On the basis of existing literature and comparison of electric and optic properties of two different materials being the carbon and nitrogen compounds, it was shown that both of them are most probably allotropic forms of hypothetical C3N4. Elaborated model of molecular structure of one of these materials is similar to that of chaoite (-C=C-), whereas model of another one shows resemblance to that of diamond. This leads to the conclusion that C3N4 is a compound similar to carbon and not to βSi3N4, and also, that various CxNy materials, which are being mentioned in literature may possibly be allotropic forms of C3N4.

E-BN layers were deposited on non-heated CaF2 and Si substrates using the method of electrostatic acceleration of h-BN powder in a high-voltage cascade accelerator. The phase compositions of the layers were examined by the XRD method — the values of d obtained were similar to those reported by Batzanov et al. [1]. IR examinations were conducted within the range 400–4000 cm−1. The molecular structure of E-BN was modelled using a computer simulation (with the Hyper-Chem computer program) based on the results obtained. The model thus obtained differs from those known earlier for h-BN, w-BN and c-BN.