Extraction of AlGaN/GaN HEMT Gauge Factor in the Presence of Traps

Repeatable gauge factors (GFs) of an AlGaN/GaN high-electron mobility transistor (HEMT) device were obtained after eliminating parasitic charge-trapping effects. Many GFs for AlGaN/GaN HEMTs are reported in the literature, and charge traps could be responsible for the four orders of magnitude variation in reported GFs. By employing continuous subbandgap optical excitation, the effect of nonrepeatable charge-trapping transients was effectively minimized, allowing the GF to be accurately measured. The measured GF (-2.8 0.4) is reasonably close to the simulated GF (-7.9 5.2) calculated from stress-induced changes in the 2-DEG sheet carrier density and mobility.