Abstract: A nitride semiconductor LED improved in lighting efficiency and a fabrication method thereof, in which an n-doped semiconductor layer is formed on a substrate. An active layer is formed on the n-doped semiconductor layer to expose at least a partial area of the n-doped semiconductor layer. A p-doped semiconductor layer is formed on the active layer. A p+-doped semiconductor layer is formed on the p-doped semiconductor layer. An n+-doped semiconductor layer is formed in at least a partial upper region of the p+-doped semiconductor layer via n-dopant ion implantation. The n+-doped semiconductor layer cooperates with an underlying partial region of the p+-doped semiconductor layer to realize a reverse bias tunneling junction. Also, an upper n-doped semiconductor layer is formed on the n+-doped semiconductor layer to realize lateral current spreading. The invention can improve lighting efficiency by using the reverse bias tunneling junction and/or the lateral current spreading.

Abstract: A nitride semiconductor LED improved in lighting efficiency and a fabrication method thereof, in which an n-doped semiconductor layer is formed on a substrate. An active layer is formed on the n-doped semiconductor layer to expose at least a partial area of the n-doped semiconductor layer. A p-doped semiconductor layer is formed on the active layer. A p+-doped semiconductor layer is formed on the p-doped semiconductor layer. An n+-doped semiconductor layer is formed in at least a partial upper region of the p+-doped semiconductor layer via n-dopant ion implantation. The n+-doped semiconductor layer cooperates with an underlying partial region of the p+-doped semiconductor layer to realize a reverse bias tunneling junction. Also, an upper n-doped semiconductor layer is formed on the n+-doped semiconductor layer to realize lateral current spreading. The invention can improve lighting efficiency by using the reverse bias tunneling junction and/or the lateral current spreading.

Abstract: Disclosed is a nitride semiconductor LED and a fabrication method thereof. An n-doped semiconductor layer, an active layer, a p-doped semiconductor layer and a p+-doped semiconductor layer are formed in their order on a substrate. A resultant semiconductor structure is mesa-etched to expose a partial area of the n-doped semiconductor layer. The p+-doped semiconductor layer and the exposed area of the n-doped semiconductor layer are n-doped at a high concentration to form first and second n+-doped regions, respectively. P- and n-electrodes are formed on the first and second n+-doped regions, respectively. Then, reverse bias is created to improve an ohmic contact structure between a semiconductor layer and a metal electrode thereby lowering drive voltage while raising overvoltage resistance and luminance.

Abstract: The air pre-cleaner includes a housing, a drain valve, and an air exhaust pipe. The housing is provided with an air inlet. The drain valve is disposed in the housing and is configured to drain impurities separated from intake air entering the housing through the air inlet. The intake air is exhausted from the housing through the air exhaust pipe. An upper portion of the air exhaust pipe protrudes inside the housing, and the air exhaust pipe has a lateral section with a first end portion that is disposed near the air inlet that is sharper than an opposite portion thereof.