ChargeTrap

Charge trap, sometimes written as charge-trap, refers to a localized energy state in a material that can capture and hold a charge carrier (electron or hole) for a finite time. These traps occur in semiconductors and insulators as intrinsic defects, impurities, interface states, or radiation-induced states. A trap’s energy level within the band gap, its depth, and its capture cross section determine how readily carriers are captured and how slowly they are released. Temperature, electric field, and occupancy influence trap dynamics.

Charge traps are typically classified as bulk traps, located inside the material, or interface traps, found at boundaries such as oxide–semiconductor interfaces. They can be shallow, with fast emission, or deep, which retain charge for long periods. Oxide traps in materials like silicon dioxide and high-k dielectrics, as well as interface traps at semiconductor–oxide interfaces, are especially important in electronic devices. External factors such as radiation exposure, stress, and aging can create or modify traps, contributing to reliability issues like bias temperature instability and threshold voltage shifts in transistors.

In devices, charge trapping influences performance and reliability. In memory technology, charge-trap flash memory stores information by trapping charges in a dielectric layer. In transistors, trapped charges cause threshold-voltage shifts and hysteresis; in imaging detectors and sensors, traps can cause persistence and reduced charge collection efficiency. Characterization techniques such as deep-level transient spectroscopy (DLTS) and related transient methods are used to identify trap energy levels, densities, and dynamics.

Chargetrap is a fundamental concept in semiconductor physics and materials science, shaping device design, performance, and long-term reliability across electronics and memory technologies.