Oxygen-related border traps in MOS and GaN devices

Oxygen-related border traps cause low-frequency excess (1/f) noise in MOS transistors with SiO₂ gate dielectrics and GaN/AlGaN HEMTs. In each case, the noise is associated with a reconfiguration of the microstructure of near-interfacial defects upon charge capture. O vacancies in the near-interfacial SiO₂ capture electrons when Si-Si bonds are stretched beyond their equilibrium length, and release electrons when the defect relaxes. These lead to MOS noise at room temperature. Oxygen DX centers in AlGaN exhibit metastable states that differ in energy by ~0.2 e V, which leads to increased noise in GaN/AlGaN HEMTs at cryogenic temperatures.