In this work, the charge storage based split floating gates (FGs) enhancement mode (E-mode) AlGaN/GaN high electron mobility transistors (HEMTs) are studied. The simulation results reveal that under certain density of two dimensional electron gas, the variation tendency of the threshold voltage (V-th) with the variation of the blocking dielectric thickness depends on the FG charge density. It is found that when the length sum and isolating spacing sum of the FGs both remain unchanged, the V-th shall decrease with the increasing FGs number but maintaining the device as E-mode. It is also reported that for the FGs HEMT, the failure of a FG will lead to the decrease of V-th as well as the increase of drain current, and the failure probability can be improved significantly with the increase of FGs number. (C) 2017 Elsevier Ltd. All rights reserved.