Influence Of Floating Metal Ring On The Characteristics Of AlGaN/GaN Heterostructures Schottky Diode

AlGaN/GaN heterogeneous structure material has became the hot topic of microelectronic in recent years because of its excellent characteristics, such as,high temperature, high frequency and high power. Heterojunction field-effect transistor (HFET) produced by AlGaN/GaN, even without doping, has a very high density of two-dimensional electron gas (2DEG) due to its strong polarization effects in the hetero-junction interface. W e make Schottky Diode with the similar process of production of making HFET, and because of the excellent advantages of AlGaN/GaN heterojunction material properties, in addition to advantages such as low power, high current, high frequency, it also does not need doping, as well as high migration rates. But the resistance pressure value of SBD maded by traditional technology are not high, main has two causes, one is that in the edge of metal contact,the curvature radius is very small, because of that,electric field stre-ngth will be very high, it makes potential barrier be thinner, thus tunnel effect will be obvious, reverse leakage current increased, reverse characteristics become "soft", it makes breakdown voltage greatly lower. Second is that there is complex surface State on the Silicon surface in the process of making contact potential barrier,and, because of oxygen pollution in the process of heat treatment,that makes reverse leakage current increased.We have a method that using a floating metal ring between two electrodes of the Schottky diode,and we expects that it can improve the performance of Schottky Diode effectively. We change the area of floating metal ring,and then we measure I-V,C-V characteristics curve and reverse characteristics of Schottky Diode with different floating metal rings, then observe and analyse that how to affect performanc of Schottky Diode.So we can optimize the area and the distance to Schottky contact electrode and the number of floating metal ring structure,and to make it on the advance of Schottky barrier diodes have a maximum level of performance. Research results indicates that: influence of floating metal ring on second dimension electronic gas density, and Schottky potential barrier height and polarization charge density of Schottky Diode is not obvious. Influence of schottky floating metal ring on pinch-off point and surface reverse leakage curren is obvious. The saturation current reduce and surface reverse leakage current increase with the area of Schottky floating metal ring increasing.