Zaven N. Adamian

Investigations of solar cells with porous silicon as antireflection layer

Abstract The possibility of using porous silicon layers as antireflection coating instead of the antireflection coatings in common silicon solar cells was investigated. A technology for the manufacture of porous silicon antireflection layers was developed. The comparison of the photovoltaic and optical characteristics of investigated samples of solar cells with ZnS antireflection coating and with porous silicon antireflection coating is presented. It is shown that the formation of the porous layer under optimal technological regimes leads to significant improvement of the main photovoltaic parameters–short-circuit current and open-circuit voltage.

Smoke sensor on the base of Bi2O3 sesquioxide

Abstract The proposed smoke sensing element is a thin film of bismuth sesquioxide made by different deposition methods by use of a corresponding heat treatment. The resistance of thin films placed in smoke medium is changed by about five orders of the magnitude at room temperature. The films influence on neutral and changed solid smoke particles on the thin film resistance was investigated. It is shown that the contribution of the particles on the resistance is negligible up to 30% of the smoke concentration in air and the sensitivity of the samples investigated is caused by gases, formed by the combustion.

Smoke sensor with overcoming of humidity cross-sensitivity

Abstract The influence of the environmental humidity on the sensors based on a thin-film γ-Bi2O3 is investigated. It is shown that relative humidity affects smoke sensing performances. To overcome the humidity cross-sensitivity, a new version of high sensitive smoke sensor with corresponding alterations in its design is proposed. The optimal operation mode when humidity cross-sensitivity becomes negligible and the smoke sensitivity reaches its maximal value is revealed. The time characteristics of the sensors under influence of the various concentration air–smoke mixtures are studied. A smoke detector processing circuit based on the considered smoke sensor sensing element is proposed. It is shown that such a smoke detector is able to operate reliably under low concentration of smoke and high relative humidity conditions.

Determination of basic parameters of porous silicon

A new simple nondestructive capacitance method is proposed for determination of the basic parameters of porous silicon such as layer thickness, porosity and dielectric permittivity. The method is based on two measurements of the capacitance of a metal/porous silicon/single crystalline silicon/metal (M/PS/c-Si/M) structure, one measurement being performed with empty pores, and the other measurement with pores filled by an organic compound with a high value of dielectric permittivity. A comparison of results obtained by the ball lap and gravimetric techniques before and after anodization with the capacitance data measurements carried out with the same samples prior to their destruction shows sufficiently good agreement.

Smoke-detector signal micrologic processing circuit

We have proposed a new simple single processing circuit on the basis of micrologic included logic NAND and OR-AND cells for an absorption type smoke-detector. The principle of the operation of the circuit is described. The merits and deficiences of such processing circuits are discussed.

Room temperature ethanol sensors based on SnO2 films

The results presented in this paper demonstrate the possibility of using tin dioxide films as sensitive elements for alcohol sensors. The tin dioxide films were deposited by the spray pyrolysis method on alumina substrates as well as on n+ porous silicon upper layer of silicon diode structures. Room temperature, under atmospheric pressure measurements of the parameters of the obtained structures revealed their high sensitivity to the mixture of ethyl alcohol vapors and air. The optimum concentration of precursor solution for precipitation of tin dioxide films and technological regimes for the deposition of tin dioxide films and formation of a porous silicon layer with appropriate thickness and porosity by electrochemical anodization were found.

Solar cells with porous silicon as antireflection layer

The possibility of using porous silicon layers as antireflection coating instead of the antireflection coatings in common silicon solar cells was investigated. A technology for the manufacture of porous silicon antireflection layers on the emitter of n+ - p junctions with the already deposited contacts grid was developed. The careful investigation of the photovoltaic and optical characteristics of solar cells with porous silicon antireflection coating compared with the performances of solar cells using a well known ZnS antireflection coating is presented. It is shown that the formation of the porous layer under optimum technological regimes leads to decrease of reflection and improvement of the main photovoltaic parameters - short-circuit current and open-circuit voltage. A means of determining the porous silicon layer thickness through capacitance measurements is suggested.