Diode _ _ technetium Technology trends planar face diode

Schottky diodes advantage: a high switching frequency and the forward voltage drop, etc., but its reverse breakdown voltage is relatively low, most not more than 60V, only up to about 100V, so as to limit its scope of application. As in switching power supplies (SMPS) and power factor correction (PFC) circuits in power switching device freewheeling diode, 100V transformer secondary with more frequency rectifier diode, RCD snubber circuit using high speed diodes and a 600V ~ 1.2kV PFC boost diodes with 600V, and only use the fast recovery epitaxial diodes (FRED), and ultra-fast recovery diode (UFRD). UFRD reverse recovery time of 20ns or more Trr are not sufficient to meet in areas such as the space station need to 1MHz ~ 3MHz with SMPS's. Even the hard-switching of 100kHz SMPS, due UFRD conduction losses and switching losses are large, the shell temperature is high, we need a larger radiator, so that the SMPS volume and weight gain, does not meet the miniaturization and light and thin trends. Therefore, the development of high voltage above 100V SBD, has been the subject people to study and attention. In recent years, SBD has made a breakthrough, 150V and 200V high-voltage SBD already on the market, the use of new materials in excess of 1kV SBD also successfully developed, so that their application has injected new vigor and vitality. Schottky diode structure: As you know, there are a lot of internal metal conductor conduction electrons. When the metal-semiconductor contacts (both from the only atomic order of magnitude), the metal Fermi level below the Fermi level of the semiconductor. The metal inside and the semiconductor conduction band energy level corresponding points, electron density is less than the electron density semiconductor conduction band. Thus, the latter two contact electrons from the semiconductor to metal diffusion, so that the metal negatively charged, positively charged semiconductor. Since the metal is an ideal conductor, negative charge is only distributed on the surface of a thin layer of atomic size. For the N-type semiconductor, the impurity atom loses electrons becomes a positive ion donor is distributed among a large thickness. Electrons from the semiconductor to the results of metal diffusion movement, a space charge region, self-built electric field and the barrier, and the depletion layer is only one side of the N-type semiconductor (semiconductor barrier region all come into the side). Barrier region in the direction of the electric field by the self point metal N-type region, with the self thermal field electron emission increases, the diffusion current in the opposite direction of the drift current increases, ultimately achieving dynamic balance between the formation of a metal-semiconductor contact potential barrier, which is a Schottky barrier. When the applied voltage is zero, the diffusion current and reverse-current electron drift equal dynamic equilibrium. In the forward biased (ie metal positive voltage, a negative voltage semiconductors), the self-built field weakened, the semiconductor side of the barrier lowering, so the formation of the metal-to-semiconductor forward current. When reverse biased, the self field enhancement, increase in barrier height, formed from semiconductor to metal less reverse current. Therefore, SBD and PN junction diodes, is a one-way non-linear device having conductive. Technetium Guangdong Electronic Technology Co., Ltd. professional production and sales Schottky diode twenty years, the current is divided into 1A, 2A, 3A, 5A, 8A, 10A, 15A, 20A, 30A, 45A, and it is widely used in various types of power consumer electronics products.