Abstract: The present invention relates to a light emitting diode having an AlxGa1-xN buffer layer and a method of fabricating the same, and more particularly, to a light emitting diode having an AlxGa1-xN buffer layer, wherein between a substrate and a GaN-based semiconductor layer, the Al x Ga 1-x N (O?x?1) buffer layer having the composition ratio x of Al decreasing from the substrate to the GaN-based semiconductor layer is interposed to reduce lattice mismatch between the substrate and the GaN-based semiconductor layer, and a method of fabricating the same. To this end, the present invention provides a light emitting diode comprising a substrate; a first conductive semiconductor layer positioned on the substrate; and an AlxGa1-xN (O?x?1) buffer layer interposed between the substrate and the first conductive semiconductor layer and having a composition ratio x of Al decreasing from the substrate to the first conductive semiconductor layer.

Abstract: A frequency detecting circuit and method and a semiconductor apparatus including the frequency detecting circuit, in which the frequency detecting circuit includes an edge detecting circuit, a clock signal generating circuit, and a determination circuit. The edge detecting circuit detects an edge of an input clock signal. The clock signal generating circuit generates a selection clock signal, which is a periodic pulse signal, in response to the detected edge. The determination circuit generates a frequency detection signal based on the number of occurrences of the selection clock signal in a period of the clock signal. The semiconductor apparatus includes the above-described frequency detecting circuit and a processor resetting the semiconductor apparatus in response to the frequency detection signal. Since a frequency is detected every half period, that is every high/low level period, of the clock signal in a digital manner, the reliability and the accuracy of frequency detection is improved.