Different technologies have been developed for the realization of AlGaN/GaN HEMTs exhibiting the normally-off functionality, such the gate recess or the introduction of a P-GaN layer for lifting-up the conduction band level under the gate. Despite their respective advantages, the major drawbacks are the degradation of the carriers mobilities in the channel due to the gate manufacturing for the first one, or the reduction in the channel conductivity for the second one because it is necessary to decrease the thickness and aluminum content of the AlGaN barrier layer to lower the 2DEG density. For avoiding these disadvantages, we propose a new concept of normally-off AlGaN/GaN HEMT with nanostructured P-GaN regions distributed along the gate, resulting in an alternation of back to back p-n junctions, thus allowing the reduction of the 2DEG density by the formation of lateral depleted areas extending through the channel of the active regions. This structure operates like a n-channel JFET device benefiting from the high electron mobility due to the AlGaN/GaN heterostructure. Unlike the conventional P-GaN HEMTs, an accurate etching of the AlGaN barrier is not required: GaN wells can go through the barrier until the underlying GaN layers while guaranteeing the normally-off behavior. We performed 2D and 3D simulations in order to evaluate the potentialities of this new structure. We have analyzed the influence of both geometrical and technological parameters of the P-GaN wells (depth, width, spacing between two wells and P-doping concentration) and of the AlGaN layer (thickness and aluminum rate) on the resulting lateral depleted areas extension and as a consequence on the on-state and off-state behavior of the HEMT. For a 100 nm depth, a 40 nm spacing, x Al = 0.20 and a P-doping concentration of 1019 cm -3 , the normally-off functionality was demonstrated with threshold voltages higher than 2.5 V. The new enhancement-mode AlGaN/GaN HEMT fabrication process with nanostructured P-GaN wells along the gate will be presented, with a focus on the selective area regrowth used for the realization of the P-GaN regions, a technology that has been validated with micrometer size patterns in a previous work for the fabrication of a normally-off P-GaN HEMT exhibiting positive threshold voltages around 1V. The difficulty here lies in the GaN regrowth in nanostructured patterns. The first technological step we have developed is the e-beam lithography of a 200 nm thick HSQ resist layer, which acts as a mask for the selective GaN regrowth, in order to define a network of 50 nm wide HSQ walls spaced 100 nm apart along the gate. The nanostructured wells are then defined by a 100 nm deep BCl 3 etching of the AlGaN and GaN layers between the HSQ walls. The next step of the process is the selective area growth of the Mg-doped GaN regions. We present in this work the study of the MBE regrowth in order to obtain a good filling of the wells with GaN.