Transition Time of GaN HEMT Switches and its Dependence on Device Geometry

Paper in proceeding, 2023

This paper presents the impact on the slow transition time of GaN HEMT switch transistor due to size and geometry. Measurements in the time domain are used to characterize the transition time of the switch from off to on. This is done for several switch transistors with variations on total gate width and number of fingers. In order to enable the comparison of transition times a figure of merit is established. This is achieved by using a commonly used model for trapping effects to quantify the amplitude of the slow transient with respect to the gate voltage. The resulting analysis indicates that transition time is sensitive to transistor size and dependent on the geometry of the device as increasing the width of the gate fingers is more advantageous compared to increasing the number of fingers.