A Schottky diode, also known as a Schottky barrier diode or hot-carrier diode, is a type of semiconductor diode formed by the junction of a semiconductor with a metal. It has a low forward voltage drop and a very fast switching action. Unlike a conventional PN-junction diode, which is formed from a piece of P-type material and a piece of N-type material, Schottky diodes are constructed using a metal electrode bonded to an N-type semiconductor. The V-I characteristics of Schottky diodes are very much similar to the PN junction diode, with current being the dependent variable and voltage being the independent variable. Schottky diodes are often used in applications where high-speed switching is required, such as in digital logic gates and circuits. They are also used in stand-alone photovoltaic systems to prevent batteries from discharging through the solar panels at night, called "blocking diodes". Compared to p-n diodes, a Schottky diode provides lower voltage drop across the diode at low reverse bias. Some applications of Schottky diodes include rectifiers in switching regulators, discharge protection in power electronics, and rectifying circuits requiring high switching rate.