Nanoscale Stress Localization Effects on the Radiation Susceptibility of GaN High‐Mobility Transistors

Abstract

Nanoscale localized mechanical stress fields develop unavoidably in microelectronic devices due to structural and processing aspects. Their global average is too small to influence bandgap or mobility, but it is proposed that stress localization can influence defect nucleation sites under radiation. This is investigated on gallium nitride high‐electron‐mobility transistors (GaN HEMTs). Using transmission electron microscopy, we spatially resolved the stress field in the AlGaN layer for both pristine and 10 Mrad gamma‐irradiated HEMTs. The quantitative nanobeam electron diffraction and geometric phase analysis indicate that tensile stressed localizations experience higher radiation‐induced strain. This finding is explained by the tensile stress dependence of the carrier concentration and mobility in the AlGaN layer. Since gamma radiation damage is inflicted by high‐energy electrons only, localized regions of higher tensile stress in the AlGaN layer are expected to be more susceptible to gamma rays.

Heavy Ion Displacement Damage Effect in Carbon Nanotube Field Effect Transistors

“…Because the damage in the Pd metal contact may be shielded by the high-density electrons and thus have little impact on the channel, the results are not shown in Figure 5a. Since single incident particles can reduce the semiconductors' crystallinity within a radius of 10 nm order-ofmagnitude, 47 the 5 × 10 12 ions/cm 2 -irradiation-induced damage is expected to result in an almost uniform distribution in the ions' incident plane. This is verified by the results shown in Figure 5a.…”

“…Although experimental − and simulation studies have studied the atomic-level dislocation generation in CNTs, the coupling between the material damage to the transistor performance degradation has not been systematically investigated. Moreover, transistors become increasingly sensitive to displacement damage as the technology node scales down. , Single incident particles can reduce the semiconductors’ crystallinity within a radius of 10-nanometer-order-of-magnitude, therefore degrading the local current-drive capacity. For deep-submicron or nanometer-node transistors, the channel’s area is comparable, if not smaller, to the damaged area by a single particle.…”

“…Moreover, transistors become increasingly sensitive to displacement damage as the technology node scales down. 45,46 Single incident particles can reduce the semiconductors' crystallinity within a radius of 10-nanometer-order-of-magnitude, 47 therefore degrading the local current-drive capacity. For deepsubmicron or nanometer-node transistors, the channel's area is comparable, if not smaller, to the damaged area by a single particle.…”