Design concepts of high energy punchthrough structures

This paper deals with the design concepts of high energy punchthrough structures. The equations for the voltage-ampere V-I characteristics of the punchthrough diodes are first derived in terms of the base doping and the base width and the maximum power handling capability is then calculated by incorporating the boundary conditions for thermal instability. A set of design curves are generated for various base width and base doping levels. Several groups of punchthrough limited p⁺-n-p⁺devices with different voltage capabilities were fabricated. The power handling and the energy handling capabilities were directly measured and the results were compared with calculated values. These diodes were successfully used in an ignition circuit as a replacement for Zener diodes to clamp the collector-base voltage of the output transistor.The diodes showed energy handling capability as high as 19 J for pellet size of 0.17 in × 0.17 in.