At present electronic X-ray sensors are in development by different institutes and industrial companies. Sensors, which operate using the scintillator technology, are used in small scope. In contrast to this the highest sensitivity and sharpness of image can be achieved with direct converting systems. Such systems are not commercially offered today yet. There is a rising requirement at electronic X-ray systems for nondestructive testing, for the customs and applications in the medical area. The proposed project is to supply the base for industrial production of directly converting GaAs X-ray sensors.

In the field of microwave technology at present the replacement of discrete realized circuits by microwave integrated circuits (IC’s) takes place. This allows the practical realization of new sensor concepts, e.g. the integration of the signal processing unit into the sensor and a better handling through drastically reduced dimensions. A complete innovation represents the combination with an air ultrasonic sensor for independent distance measurement. In this way apart from the measurement of the received signal amplitude a unique phase measurement becomes possible.

The objectives of the proposed project are to improve and adopt GaAs-technology to create new highly integrated sensor microsystems for non-destructive evaluation systems for industrial quality assurance.

The present project is an integral part of the common project «Development of a microsystem-platform of industrial quality assurance on the base of GaAs-sensors». It includes developments from the concept up to the demonstrators for x-ray sensors and microwave sensors.

The common project shall establish the scientific and technological requirements for the future development of microsystems based on GaAs sensors. The project prepares an international platform for future prototype developments of GaAs-based measurement and testing systems optimized to the needs of industrial non-destructive and contactless evaluation and quality assurance.

The designers of the systems are Fraunhofer Institut fuer Zerstorungsfreie Pruefverfahren (IZFP) in Saarbrьcken (microwave sensors) and the laboratory Fraunhofer Einrichtung fuer akustische Diagnose und Qualitaetssicherung (EADQ) in Dresden (X-ray sensors).

The semiconductor «filling» of the sensors will be developed and fabricated in the RPC «Electron Technology», TSU, where extremely favourable conditions have been created for execution of this work. The RPC specialists, who for years had been engaged in development of purpose-specific IC's and semiconductor devices for the defense industry, redirected their talents to peaceful activities. The level of their developments and technology is growing steadily and device nomenclature is being broadened. This is essentially due to successful completion of the ISTC project G-10A/B (1994-97) and execution of the current five-year NATO SfP Project ENABLE. Under these projects digital and analog GaAs IC's for communication systems have been and are being developed. Main results were reported at various international forums and published in scientific journals.

In addition, the RPC has received as a grant tens of items of up-to-date technological and measuring equipment from Infineon Technologies (Munich, Germany). The equipment has been delivered to Tbilisi and is to be installed.

Two teams of specialists from other institutions will participate in the proposed ISTC project: in development and fabrication of photomasks (F.Lukin Research Institute of Physics of Semiconductors, RIPP, Moscow-Zelenograd, Russian Federation) and in creation of a foundry service for future production of devices («Electron Technologies» Ltd. MION-7, Tbilisi, Georgia).

According to the project goals the project is organized in a way, which enables the RPC to reach a high standard GaAs-technology foundry service and demonstrates its new quality by developing two types of innovative sensors with industrial relevance.

To achieve the project objectives two types of sensors are to be developed for developers of non-destructive evaluation systems (IZFP):

– x-ray sensors for high resolution x-ray imaging (XRS);

The expected project results include:

– creation of infrastructure with the installed new equipment and mastered technological processes (formation of 0.6-0.7 mm metallization lines, deposition of various metal compositions, evaporation of Si₃N₄ dielectric layers, etc.);

Most important expected scientific results include:

– definition of the architecture and parameters of the starting material by correlation of its electric and structural properties with the optimal X-ray detection behavior (in close cooperation with the partner and collaborator);

On this stage the partner project is an applied research project without direct commercial benefit. However the scientific and technological results generate a base for development of demonstrators of a new generation of x-ray and microwave sensors for the application in non-destructive testing. Commercially the X-ray sensor developments are already interesting by the fact that alone in Germany about 100 million radiographs are made annual. At present only 1% of the assigned devices operate digitally. A very small section of it possesses direct-converting sensors. By the beginning conversion to digital radiography it is to be counted on an important demand for direct-converting X-ray sensors in the next years.

Microwave sensors on the basis of GaAs IC's can be manufactured with sufficient number of items importantly more cheaply than conventional ones. This circumstance provides an important market advantage for them.

Thus on a later stage the NDE-systems shall be produced by transferring the acquired results to industry. The RPC together with MION-7 can act as foundry service for the production of the GaAs-chips.

In the framework of the present project main ISTC goals and objectives should be met: redirecting the specialists activity from military to peaceful purposes and further integration of scientists into the international scientific community; developing of applied research the results of which will be in industrial demand.

The scope of activity is defined by the goals and the expected end results.

To realize the above-mentioned goals the project is divided into five main tasks: the preliminary period, development of XRS, development of MS, device optimization, creation of XRS and MS demonstrators. The preliminary period – preparation of scientific and technical bases for project realization, is followed by simultaneous development of both sensor types which then will be optimized to achieve the end result: the GaAs semiconductor technology for two types of devices shall be defined, stabilized, documented and applied to implement key functions in state-of-art non-destructive diagnostics microsystems.

The technical approach and methodology involve different aspects of project activity aimed at its successful implementation with allowance for the fact that the work will be done in two independent directions.

As for work organization, a system of cooperation with the partner and the collaborator, as well as main questions of supplies at different stages of work will be elaborated.

The problems of development of the concept and approaches to XRS (especially in selection and investigation of a starting material) and MS build-up are singled out.

Measuring methods and technological processes to be developed in the course of project implementation are defined.

The terms of delivery of intermediate and final XRS and MS demonstrators to the partner are established.

The organizational structure for the project is developed and the functions are distributed among the project executors.

The main function of the partner (IZFP, EADQ) consists in the definition of the subtasks, quality control, the assembly and line-up of the complete sensor-demonstrators and the common project management. Further they process different scientific functions, e.g. the simulation of the interaction between photons and semiconductors in the X-ray sensor part or the development of the signal evaluation algorithms in the microwave sensor part.

The collaborator – Dr.Roland Diehl (Fraunhofer Institut fuer Angewandte Festkoerperphysik), participates in selection of a starting material for semiconductor sensors, helps in distribution and execution of orders for material fabrication. The collaborator participates in discussion of intermediate and final project results, gives advice on important questions.