The semiconductor device includes a P-type group III-V nitride semiconductor layer, an N-type group III-V nitride semiconductor layer, and an electrode in contact with both of the P-type group III-V nitride semiconductor layer and the N-type group III-V nitride semiconductor layer. The method can comprise: attaching an anchoring compound to a nanoparticle; attaching a RAFT agent to the anchoring compound; and polymerizing a plurality of butadiene-derived monomers on the anchoring compound to form a polymeric chain covalently bonded to the nanoparticle via the anchoring compound. Through the active reduction in the resistance tolerance, the requirements placed on the electric strength of the balancing transistors as well as energy losses of the balancing circuit are reduced. The handle casing is fixed around the handle to hold the press portion.