**4. Functional fianite films on Si, Ge and GaAs substrates**

#### **4.1 Techniques for deposition of fianite films on Si and GaAs substrates**

In recent years a considerable attention was drawn to fianite films on silicon due to its electric and optic device applications, such as isolating layers in SOI (silicon-on-insulator) devices [32], gate dielectric in Si- [33, 34], SiGe- [35] and AIIIBV -based [36] device structures, buffer layers for producing of optic coatings of films of various semiconductors [37–40], superconductors [41-43], ferroelectrics, etc.

Fianite in Photonics 155

of magnetron systems, is achieved by an increase of the ion current density due to localization of plasma by means of high transverse magnetic field. The increase of sputtering at simultaneous decrease actuation gas pressure allows a significant decreasing contamination of the films by alien gas impurities. Fianite was grown up on Si and GaAs substrates using unbalanced magnetron system. Fianite crystals were used as a target. Si substrate subjected to the sputtering was heated by IR radiance. Preparation of the substrates included degreasing, removing of the oxide and passivating of the surface in ammonium-peroxide solution. Optimization of the conditions of the growth of fianite films on Si substrates was carried out by varying of the sputtering rate, temperature of the

Bombardment of the target leads to dissociation of zirconium and yttrium oxides to ZrO, Zr, YO, Y, O2. That is why such parameters as sputtering rate and residual gas pressure considerably influence on stoichiometry of the resulting film. Energy of the evaporating particles is rather low (0.5-10 eV), so for the epitaxial growth of fianite film a high

Experimental installation for deposition of fianite films was a sputtering system composed by vacuum device and eximer laser. The system has been designed and manufactured in

Operational oxygen pressure was maintained by vacuum system supplied with a mechanical pump and СНА-2 letting system. Evaporation of the target was performed by LPX200 eximer laser radiation working on KrF mixture. Wavelength of the radiation was 248 nm, pulse duration 27 ns, the pulse energy 350 MJ (pulse power 1.3×107W), repetition frequency 50 Hz. Optical system providing a focusing of the laser beam on the target surface consisted of qurtz prisms and 30 cm focal distance lens. The laser beam spot on the target surface was 1×4mm2. The energy density on the target surface was ~10 J/сm2. The distance between the target and substrate was 60 mm. Cylindrical targets of 15-20 mm diameter and 10-30 mm length were used in the installation. In order to prevent local overheating of a target and to provide uniform material drift rotation and axial movement of the target was used. Possibility of conducting pre- and post-growth annealing under oxygen atmosphere at 10 Pа – 100 kPa pressure and at up to 750ºС temperature is a peculiarity of

Ceramic target of (ZrO2)1-x(Y2O3)x with x=0.1 composition was used for deposition of fianite films. The deposition was carried out on Si and GaAs substrates heated to 600-800ºС temperature under oxygen atmosphere at approximately 10 Pа. The growth rate of YSZ films was about 0.02 nm per pulse. Contactless heater of substrates (heating by irradiance) was an original peculiarity of the sputtering system. The heater comprises vertically positioned quartz tube (of 30 mm inner diameter) supplied with refractory stainless steel heating coil on its outer surface with up to 1 kW power of the heater. Monitoring and maintenance of the assigned temperature (with 5С precision) were carried out using precise regulating device and Pt-Rh thermocouple positioned under the heating coil. A substrate was fitted in a holder and positioned inside of the quartz tube. Loading of

substrates and oxygen supply was maintained through the upper end of the tube.

temperature of Si substrate and optimal rate of the condensate supply are necessary.

substrate and residual gas pressure.

**4.2.2 Laser sputtering technique** 

IPM RAS.

the installation.

Various techniques can be used for the producing of fianite films on silicon and other semiconductors, including magnetron [39, 40, 44-46], laser and electron-beam [47-49] sputtering, molecular-beam epitaxy (MBE), as well as gas-phase chemicаl deposition [50]. The choice of a specific technique is determined by further designation of a fianite film, possibility to produce the film of maximum structural perfection, as well as technologic potentialities of a technique. So, MBE technique is more suitable for deposition of the thinnest fianite film for the use as a gate dielectric. Magnetron and laser sputtering are more favorable for fianite layers used as buffer layers with subsequent growing semiconductor films, including АIIIBV compounds. In [39] fianite films were deposited on Si and GaAs substrates using magnetron, laser and electron-beam sputtering techniques. The films
