Mettalic Behavior of Two-Dimensional Semiconductors

Northeastern University, Boston MA

Investigators

Abstract

Metal-insulator (M-I)transitions in two-dimensional semiconductors will be investigated in this project. This phenomenon was first observed several years ago in silicon-base two-dimensional electron systems and later reproduced in other two-dimensional systems. The underlying physics of this phenomenon is not understood, in spite of several proposed models (new types of superconductivity, non-Fermi liquid state, formation of a Wigner glass) and a growing number of theoretical and experimental papers. In the present project, the capacitance and chemical potential of two-dimensional systems will be measured along with their transport and magneto-transport properties at milliKelvin temperatures. These measurements will provide information about density of states, compressibility, and possibly about magnetic properties of the unusual metallic state. They will show how these properties change at the M-I transition and in an external magnetic field. The information obtained is expected to be crucial for the understanding of the nature of the M-I transition in two dimensions. Graduate and undergraduate students will participate in this research and will thereby be trained in a complex and important area of forefront physics, become familiar with semiconductor device technology, and will be excellently prepared for future employment in industry, government or education. *** This project comprises an advanced research program in the properties of semiconductor materials, in which the interactions between electrons dominate the physical properties and often lead to new, unexpected phenomena. This research stands at the forefront of condensed matter physics and materials science. The questions addressed in this research are of fundamental importance, and the answers are expected to contribute to the understanding of materials at the most basic level. The project will provide an excellent introduction for graduate and undergraduate students in a cutting edge area of physics. They will become familiar with semiconductor technology, relevant research methods, and will be prepared for future employment in industry, government or education. %%%