Abstract of the project:
Based on a newly discovered phenomenon in solid-state structures by the Project team - a magnetically controlled surface current in solid-state structures, which is a linear and odd function of the supply and magnetic field, a new non-destructive method for Surface characterization is proposed. This current, apart from providing a novel consistent interpretation of the classical Hall effect, is highly sensitive to the boundary conditions. Its behaviour is related with the defects, dislocations, dopant states, deformations and so on, available there. This exceptionally important peculiarity of the new effect provides to examination the properties of the crystal structures surface, such as, semiconductor ones. The preliminary results with silicon samples show that deformations change in a specific way the magnetically controlled current. The identification of the surface state will be performed using the individual peculiarities of the dependence of the surface current on the magnetic field, stored in an experimental database. The new method consists in the measurement of the surface current in the structures by two ohmic contacts, located on the investigated substrate plane. The individual boundary regions will be scanned by shifting of these probes along this surface, and information about the adequateness of the relevant silicon wafer used for micro- and nano-technology processes will be obtained. The implementation of the novel non-destructive approach will provide to overcome a significant part of the drawbacks of the similar methods used so far, such as high temperature, preliminary information about surface electrons and holes mobility, data about the „quick” and „slow” states, use of model coefficients in the final result and more. The suggested approach provides the possibility for experimental investigation of surfaces with previously unknown properties, which is one of its key advantages. The simplicity of the circuitry and the clear theoretical background of the new method warrant its wide research and industrial applicability.
Project objectives and hypotheses
The objective of the project is to propose a new, applicable mainly in the semiconductor structures for surface investigation of solid-state structures in wide temperature range, which is based on the strong sensitivity of the magnetically controlled surface current generated by the state of this surface. This objective is also aimed at establishment and future development of the scientific capacity of the Institute of Systems Engineering and Robotics – BAS, in such perspective fields like sensorics, microsystems, and nano-science through implementation of the tasks specified under the Project. The scientific hypothesis is: Scientific and experimental implementation of a new original and innovative non-destructive method, applicable in micro- and nano- technology, for surface investigation of solid-state structures by magnetically controlled surface current within a wide temperature range. This approach will provide to overcome a material part of the problems and drawbacks of the used methods. The simplicity of the experimental setting and the clear theoretical background of the suggested innovation justify its realism and warrant a wide applicability and potential in Surface science. The proposed method provides the possibility for experimental investigation of surfaces with previously unknown properties, which is one of its key advantages. The above described magnetically controlled surface current will be in the basis of an original and innovative non-destructive method for surface investigation, which is expected to have indisputable advantages, and will be an important practical applicability.
Research methodology and techniques
The research methods, associated with this project, are based on the interaction of magnetic field with the kinetics of charge carriers, located in near-surface areas of semiconductor structures. The electrical, galvanomagnetic and temperature studies of magnetically-controlled surface current are key to achieving the goals of the project. The used techniques will include magnetic measurements by electromagnet with adjustable induction up to 3T and water cooling, as well as precision measuring tools and instruments for current, voltage, impedance, frequency and temperature. As a determining parameter, the magnetic field will be measured by three-component magnetic probe. The temperature experiments will be carried out by means of a cryostat with adjustable temperature ranging from -200 ° C to + 100 ° C. As coolant, liquefied nitrogen will be used.