2003/03/27 by E. Helgren, N. P. Armitage, G. Grüner +1 · 1 citation
Engineering · Physics and Astronomy · #Quantum and electron transport phenomena #Semiconductor Quantum Structures and Devices #Semiconductor materials and devices #cond-mat.dis-nn #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.69.014201
arxiv created 2003/03/27 · openalex publication_date 2004/01/13 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Results of dc and frequency-dependent conductivity in the quantum limit---i.e., \ensuremath\Elzxh\ensuremathω>kBT---for a broad range of dopant concentrations in nominally uncompensated, crystalline phosphorous-doped silicon and amorphous niobium-silicon alloys are reported. These materials fall under the general category of disordered insulating systems, which are referred to as electron glasses. Using microwave resonant cavities and quasioptical millimeter-wave spectroscopy we are able to study the frequency-dependent response on the insulating side of the metal-insulator transition. We identify a quantum critical regime, a Fermi glass regime, and a Coulomb glass regime. Our phenomenological results lead to a phase diagram description, or taxonomy, of the electrodynamic response of electron glass systems.