Abstract: The present invention relates to a short wavelength ZnO light emitting device and the manufacturing method thereof, which forms materials of p-type by doping Zn on InP, deposits a thin layer of ZnO on an upper surface of the doped layer and forms a p-n junction, thereby obtaining a stable crystal structure and enhances the effectiveness. The short wavelength ZnO light emitting device comprises a Zn doped InP layer of p-type formed by doping Zn on a substrate of InP and then replacing In with Zn; and a ZnO layer deposited on the Zn doped InP substrate whereby a forward bias voltage is applied to the doped InP and the ZnO layers, which are doped Zn, thereby obtaining a light emitting characteristic of short wavelength. A ZnO-based semiconductor light emitting device can be used as a blue and purple light source, and is expected to have more excellent characteristics in displays.

Abstract: An apparatus for measuring the focus of a light exposure system for selectively exposing a photosensitive plate to light rays in a process of fabricating a semiconductor device, wherein there is provided a focus measuring part having opaque region, transparent region, and a transparent electrode arranged in the transparent region, a conducting stage supporting the photosensitive plate; and a capacitance detector for measuring the capacitance between the transparent electrode and the conducting stage.

Abstract: A focus test mask for a projection exposure system, a focus monitoring system using the same, and a focus monitoring method include a transparent substrate and a focus test pattern formed on the substrate. The focus test pattern includes a first light shielding pattern and a second light shielding pattern placed inside the first light shielding pattern. Both light shielding patterns have fine protruding patterns arranged along edges of respective first and second closed geometric shapes defining the light shielding patterns. The focus test pattern projected onto the surface of the object allows quantitative measurement of the optimal focuses of the projection exposure system. By using the focus test mask for a projection exposure system, the optimal focuses of the projection exposure system can be periodically measured easily and precisely.

Abstract: A refrigerator door switch system for sensing opening of a freezer compartment door and a fresh food compartment door comprises a push button switch installed at the freezer compartment door or the fresh food compartment door, being positioned at a first position for stopping a fan motor for a cool air supply and turning on a cabinet lamp when the freezer compartment door or the fresh food compartment door is opened, and being positioned at a second position for driving the fan motor and turning off the cabinet lamp when the freezer compartment door and the fresh food compartment door are closed; and a switch operation cam installed at the fresh food compartment door or the freezer compartment door, corresponding to the push button switch for positioning the push button switch to the first position when the freezer compartment door or the fresh food compartment door is opened, and for positioning the push button switch to the second position when the freezer compartment door and the fresh food compartment doo