Analysis of a junction termination structure for ideal breakdown voltage in p-n junction devices

Electric-field distribution and avalanche breakdown voltage in reverse-biased p-n junction devices having a concave p-n junction termination structure are analyzed by a two-dimensional numerical method. It is shown that there are two peaks in the electric field of the device. One peak, near the p-n junction edge, is smaller than the other peak, found in the one-dimensional region, so that an ideal breakdown voltage can be obtained. This desirable feature comes partly from the excessive spreading of the depletion layer around the p-n junction edge due to the concave junction shape. One of the merits of this junction termination structure is that the allowable range of device parameters for the ideal breakdown voltage is much wider than for any other junction termination structure. Experimental breakdown voltage of a diode with the concave p-n junction structure agrees well with the ideal breakdown voltage calculated in the one-dimensional region of the device.