A method of making a semiconductor device includes forming a first conductivity type polysilicon layer over a substrate, forming an insulating layer over the first conductivity type polysilicon layer, where the insulating layer comprises an opening exposing the first conductivity type polysilicon layer, and forming an intrinsic polysilicon layer in the opening over the first conductivity type polysilicon layer. A nonvolatile memory device contains a first electrode, a steering element located in electrical contact with the first electrode, a storage element having a U-shape cross sectional shape located over the steering element, and a second electrode located in electrical contact with the storage element.