Make experiments more efficient: Two simple and powerful approaches. Mg2Si growth for photovoltaic and thermoelectric applications

Title : Make experiments more efficient: Two simple and powerful approaches. Mg2Si growth for photovoltaic and thermoelectric applications

Abstract:

Film growth and surface/interface processes are crucial in many modern technologies, including Si-based microelectronics. We introduce two original approaches effective in film synthesis and investigations.

The narrow band silicide Mg₂Si attracts attention of researchers because it has good perspectives for applications in solar cells and thermoelectric elements, consists of ecologic, abundant and rather cheap components. However, the synthesis of Mg₂Si films on Si surface is problematic: at low T Mg does not intermix with Si but at high temperatures (HT) the deposited Mg re-evaporates without film formation. Thus, Mg/Si is a good model system for demonstration of advantages of our approaches. Basing on the analysis of the deposition kinetics, we explain how and why Mg₂Si can be grown on Si at HT by ultra-fast deposition. The exothermic reaction process takes ~ 0.1 – 100 s., the process similar to Self-Propagating High-temperature Synthesis can be easily recorded with a phone camera. The obtained films have the best crystal quality and excellent electrophysical parameters.

To study different physical and chemical processes  on surfaces/interfaces (film growth, reactions, phase transformations etc), multiple experiments are usually carried out; they are time and resource consuming. If the sample has a wedge-shaped temperature distribution on the surface, different processes can be studied in the whole T range in a single experiment. Thus, one experiment can be enough to obtain the dependences of process parameters on T; the exact value of the optimal T can be found immediately and directly. We demonstrate how the T ranges of ~ 600 –850 K can be obtained due to the Peltier effect in low resistivity Si samples. Using this approach, the number of experiments necessary for achieving the result can be radically reduced. Thus, the efficiency of experimental work can be significantly increased.

Audience Take Away Notes:

• The both presented experimental approaches are simple and can be easily reproduced in the any laboratory
• The described techniques allow to enhance the efficiency of studying many T-dependent processes (diffusion, reactions, phase transformations etc) on different surfaces or interfaces
• The scientists using these methods will be able to obtain more precise results, spending less resources, within less time

Biography:

Alexander S. Gouralnik worked in the Artificial Intelligence Department at the Laboratory of 3D Microelectronics, Institute of Automation and Control Processes (IACP FEB RAS) in Vladivostok, Russia, from 1976 to 1979. Since 1979, he has been affiliated with the Laboratory of Optics & Electrophysics of Nanostructures at IACP FEB RAS.

Scientific interests : Selective and controlled film growth; physical and chemical processes on surface and interface; UHV deposition; silicide films; semiconductors; layered structures; photovotaics; thermoelectrics; optoelectronics; nanomagnetism.