Suho i mokro jetkanje AIIIBV materijala za optoelektroničke naprave

Several AIIIBV materials (InP, GaAs, AlGaAs) were etched in a reactive ion etcher using different gas compositions (CH4, H2, CH4+H2, BCl3, BCl3+H2). The influence of gas pressure, composition of mixture and RF power were examined. In BCl3 plasma, etching rate of InP was 10 nm/min, of GaAs about 300 nm/min and of AlGaAs up to 650 nm/min. The increase of the etching rate in BCl3 and H2 mixture is caused by a synergistic effect (not only by superposition of etching rates due to a chemical and physical interaction). Etched surfaces were observed by scanning electron microscope. Measurements by secondary ion mass spectrometry were involved into the discussion of the surface contamination. The BCl3 reactive ion etching process of AIIIBV is applicable for deep mesas in optoelectronics devices.Nekoliko AIIIBV materijala (InP, GaAs, AlGaAs) su reaktivno ionski jetkani različitim plinskim smjesama (CH4, H2, CH4+H2, BCl3, BCl3+H2). U BCl3 plazmi brzina jetkanja InP bila je 10 nm/min, GaAs oko 300 nm/min, a AlGaAs do 650 nm/min. Jetkane su površine proučavane skanirajućim elektronskim mikroskopom. Reaktivno ionsko jetkanje u BCl3 može se primijeniti za duboke utore optoelektroničkih naprava

Tankoslojna podloga za dvoslojeve lipida

A strip thin-film support consisting of compact or planar interdigitated array electrodes and glass substrate is presented. A novel method of forming of s-BLM on the thin metallic film (sl-BLM) has been developed. Electromechanical characteristics of BLM were studied and the measured value of elasticity modulus perpendicular to the bilayer plane was found to change considerably with increasing dc voltage. The presented results evidence the fact that the values of E^ are are strongly influenced by the degree of roughness of the metal surface. It is shown that sl-BLM modified by electron carrier can be used as a simple pH sensor.Opisuje se podloga u obliku tanke trake koja se sastoji od nizova kompaktnih ili ravnih elektroda i staklene osnove. Razvijena je nova metoda pripreme dvoslojne lipidne membrane (s-BLM) na tankom metalnom sloju (sl-BLM). Proučavana su elektromehanička svojstva BLM i mjeren je modul elastičnosti okomito na površinu dvosloja za koji se ustanovilo da se znatno mijenja s DC naponom. Izloženi rezultati ukazuju da na vrijednosti elastičnog modula E⊥ jako utječe stupanj neravnosti površine metala. Izmijenjen sl-BLM može se upotrebljavati kao jednostavna pH proba

Optimization of capacitive affinity sensors: drift suppression and signal amplification

The detection limit of capacitive affinity sensors based on the gold±alkanethiol system can be improved by optimization of sensor preparation and by signal amplification. The dissociation of the gold±sulfur binding is often a critical point leading to operative errors of such sensors. The stability of self-assembled monolayers prepared with different thiols on gold electrodes in aqueous and organic solvents was studied by the capacitive technique. The results show that monolayers made of 16- mercaptohexadecanoic acid are stable in aqueous solution and can be hardly extracted from a gold surface by ethanol, methanol, or dioxane, while a considerable damage of self-assembled monolayers was observed due to incubation in chloroform or dimethylformamide. In contrast, self-assembled monolayers made from short-chain disulfides or thiols (such as 3,30-dithio-bis(propionic acid N-hydroxysuccinimide ester) or 11-mercaptoundecanoic acid) displayed a poor stability in aqueous phase. Capacitive affinity sensors based on these short-chain thiols showed a considerable drift of the signal. The use of long-chain thiols resulted in a stable signal; it was applied to compare capacitive effects due to immobilization of different biological molecules and for preparation of different biosensors. The response of capacitive biosensors can be amplified by formation of a sandwich structure. This principle was illustrated by subsequent adsorption of polyclonal anti-HSA after binding of HSA with a sensor for HSA based on monoclonal antibodies

Self-assembled monolayers as selective filters for chemical sensors

The lateral electrical conductivity of gold layers with thickness in the nanometre range was found to decrease due to adsorption of mercury, water, iodine and sulphuric compounds onto the gold surface. A self-assembled monolayer of hexadecanethiol, deposited on the gold surface, blocked the effects of water and volatile sulphuric compounds on the lateral conductivity of the gold layers, but does not block the effects of iodine and mercury. The results indicate a selective permeability of hexadecanethiol monolayers for mercury vapour, thus providing a method for development of ultrathin filters for chemical sensors