In this work, we perform an in-depth analysis of electron-trapping in AlGaN/GaN Schottky barrier diodes under constant voltage (VAC = -100 V) off-state stress conditions. The current-voltage (I-V) characteristics of the diode after stressing show a leakage reduction and on-state degradation due to electron-trapping occurring in the vicinity of the Schottky contact. Capacitance-voltage (C-V) measurements confirm an increase of the barrier height and the on-resistance of the stressed device. Furthermore, the on-resistance increase has been studied with different temperatures and stressing times. By TCAD simulations, a lateral extension of the "trapped region" at the AlGaN/Si3N4 interface has been visualized and can qualitatively explain the phenomenon of higher on-resistance increase at higher temperatures.