Abstract: A semiconductor structure is provided. The semiconductor structure includes a substrate, a channel layer, a barrier layer, a compound semiconductor layer, a gate electrode, and a stack of dielectric layers. The channel layer is disposed on the substrate. The barrier layer is disposed on the channel layer. The compound semiconductor layer is disposed on the barrier layer. The gate electrode is disposed on the compound semiconductor layer. The stack of dielectric layers is disposed on the gate electrode. The stack of dielectric layers includes layers having different etching rates.

Abstract: A concrete bolt includes a hexagonal head part and a bolt body extended from the head part. A bottom end of the bolt body is a bevel, a surface of the bolt body has high-tooth and low-tooth threads helically extended and arranged alternately. A tooth end of the high-tooth thread is tilted outward, an end surface facing toward the head part is concaved, the low-tooth thread is roughly in a trapezoidal shape and a high-tooth thread adjacent to the bottom end has petal-shaped teeth arranged alternately. When locking into concrete, the bolt is operated more easily to save labor work by cutting with the high-tooth threads and guiding and balancing functions with the low-tooth threads. Additionally, the concrete cut is coagulated after locking, thus the bolt is more robust by having a high tensile strength and easily dismantled for repetitive use, thereby improving a practical value of the concrete bolt.