Trapfilling

Trapfilling is a term used in several scientific disciplines to describe the process by which traps—localized states that can capture particles, charges, or molecules—become occupied. Because the term lacks a single universal definition, its precise meaning is field dependent.

In semiconductor physics, traps are energy levels within a band gap that can capture electrons or holes. Trapfilling describes the transition of traps from empty to occupied states, often triggered by illumination, electric fields, or thermal activation. Occupancy affects carrier lifetimes, recombination rates, and device performance, including photoconductivity and dark current in detectors and solar cells.

From a materials chemistry perspective, traps can be adsorption sites or defect centers in porous solids such as zeolites, MOFs, or carbon materials. Trapfilling refers to the progressive occupation of these sites by guest molecules or reaction intermediates during adsorption, catalysis, or gas storage. The extent of trap filling influences adsorption isotherms, capacity, selectivity, and catalytic behavior.

In spectroscopy and solid-state physics, filling of trap states can lead to persistent photoconductivity or trap-assisted transport. Light exposure or thermal energy can release stored carriers, returning the material toward its initial state; the dynamics of trap filling are a focus of defect-physics research and device engineering.

Because the term is used informally in multiple subfields, definitions are not always interchangeable. Care should be taken to interpret trapfilling within the specific theoretical and experimental context.

See also: trap states, defect chemistry, adsorption isotherms, persistent photoconductivity, trap-assisted transport.