Abstract: A method for forming a high electron mobility transistor is disclosed. A mesa structure having a channel layer and a barrier layer is formed on a substrate. The mesa structure has two first edges extending along a first direction and two second edges extending along a second direction. A passivation layer is formed on the substrate and the mesa structure. A first opening and a plurality of second openings connected to a bottom surface of the first opening are formed and through the passivation layer, the barrier layer and a portion of the channel layer. In a top view, the first opening exposes the two first edges of the mesa structure without exposing the two second edges of the mesa structure. A metal layer is formed in the first opening and the second openings thereby forming a contact structure.

Abstract: A waterproof flashlight device for umbrellas comprises a shell made of transparent soft material, a circuit board, at least a battery, and a self-control switch. The shell has a seat installed inside. The seat is joined with a stage having a hollow chamber inside through a waterproof grommet. The circuit board is installed inside the stage. The flashlight circuit on the circuit board connects to at least a battery. The self-control switch connects the battery with the flashlight circuit. The self-control switch has two soft circuit boards. A metal ball is lapped on one of the two soft circuit boards. When the user unfolds the umbrella at night, the metal ball will contact the two soft circuit boards, and the battery will provide electricity to the flashlight circuit. The flashlight circuit will thus flash when there is no sufficient light outside.