Valensbåndinformasjon

Valensbåndinformasjon refers to the information and data describing the valence band in crystalline solids. The valence band is the highest range of electron energies that is typically filled with electrons at zero temperature. Valensbåndinformasjon includes the energy dispersion (band structure), bandwidth, the density of states, and the position of the valence-band maximum relative to the Fermi level. It also covers the character of the states (bonding, antibonding, orbital composition) and how these states evolve with changes in composition, strain, or temperature.

In semiconductors and insulators, the valence band is separated from the conduction band by a band gap, and the details of the valence band determine hole transport and optical transitions. In metals, valence and conduction bands may overlap, leading to metallic conductivity without a well-defined gap. The valence-band information is essential for understanding charge carrier dynamics, optical absorption, and recombination processes.

Measurement and theory: Valence-band information is obtained experimentally through ultraviolet photoelectron spectroscopy (UPS) and angle-resolved photoemission spectroscopy (ARPES), which map occupied valence states and their dispersion. Scanning tunneling spectroscopy can provide local valence-band features. Theoretically, band structures are calculated with methods such as density functional theory or tight-binding models, yielding energy-momentum relations and effective masses for valence states.

Applications: Knowledge of the valence band informs the design of semiconductor devices, optoelectronic materials, and photovoltaic absorbers, where hole mobility and valence-band alignment are critical.