Theory of Persistent, P-Type, Metallic Conduction in C-GeTe
Abstract
It has been known for over 20 years that rhombohedral c-germanium telluride is predicted to be a narrow gap semiconductor. However, it always displays p-type metallic conduction. This behavior is also observed in other chalcogenide materials, including Ge2Sb2Te5, commonly used for optically and electrically switched, non-volatile memory, and so is or great interest. We present a theoretical study of the electronic structure or the perfect crystal and of the formation energies of germanium/tellurium vacancy and antisite defects in rhombohedral germanium telluride. We find that germanium vacancies are by far the most readily formed defect, independent of Fermi level and of growth ambient. Moreover, we predict that the perfect crystal is thermodynamically unstable. Thus, the predicted large equilibrium densities of the germanium vacancy of ^5 x 10(exp 19) cm(exp -3) results in a partially filled valence band and in the observed p-type conductivity.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2005
- Accession Number
- ADA440113
Entities
People
- Aidan P Thompson
- Andrew C. Pineda
- Arthur H. Edwards
- Harold P. Hjalmarson
- Marcus G. Martin
- Peter A. Schultz
Organizations
- Air Force Research Laboratory