Alfred Porst

Improvement of the diode characteristics using emitter-controlled principles (EMCON-diode)

In this paper it is shown experimentally how the shape and the amount of the carrier distribution in the middle region of a diode influences the static behavior (voltage-current characteristic), the dynamic behavior (reverse recovery current, reverse recovery charge, soft recovery) and the temperature dependence of these characteristics. By combining the lifetime dominated Hall-principle and the emitter-controlling Kleinmann-principle various diodes were manufactured and investigated. With an infrared absorption technique the corresponding carrier distributions were measured.

A low loss/highly rugged IGBT-generation based on a self aligned process with double implanted n/n/sup +/-emitter

A new 1200 V-IGBT chip is presented which has an optimized planar cell structure for lowest on-state voltage, but that nevertheless guarantees a very high degree of ruggedness. The key point for these features is a new self aligned process concept with a double implanted submicron emitter structure, which will be the basis also for a lower voltage IGBT (600 V) as well as for high voltage IGBTs (1600 V and higher).

Improved 3.5 kV IGBT-diode chipset and 800 A module applications

A major feature of the improved IGBT-diode chipset is the quasi temperature independent switching losses. The temperature coefficients of the diode on-state voltage and the IGBT saturation voltage are positive. The cell area portion of the IGBT is optimized with respect to a low saturation voltage and short-circuit current. Due to the negligible recombination within the n base of the used NPT-IGBT structure, the short circuit current is independent of the collector emitter voltage.

Progress in development of the 3.5 kV high voltage IGBT/diode chipset and 1200 A module applications

A 3.5 kV IGBT/diode chipset is presented with a large safe operating area for 1200 A module applications. The IGBT cell design is optimized with respect to a low saturation voltage and a low short circuit current and the carrier modulation of the diode bases on emitter controlled principles. The turn on, turn off and short circuit ruggedness is experimentally proofed for 2.5 kV circuit voltage and 125/spl deg/C temperature. The turn off behavior is performed for the twofold nominal current of 2.4 kA and the short circuit ruggedness is verified for a period over 20 /spl mu/s. The turn on and turnoff energies show a linear dependence with the collector current.

The transistor behavior in a circuit with a shorted load

If a transistor is working in a circuit with a shorted load, two different cases have to be distinguished. Case 1 is when a transistor is switched on in a circuit with a shorted load. This case was treated in the past. A second case that has to be considered is when a short occurs during the on state of the transistor. The results of one-dimensional simulations for case 2 show that collector-emitter voltage at the transistor depends strongly on the current density, with the maximum field occurring at the n/sup -/n/sup +/ junction of the collector. During the first critical time interval, the metallurgical p-n junction has no influence. The high current densities occurring during the short can produce electric fields higher than 10/sup 5/ V/cm. These current-induced high electric fields result in a current runaway causing, finally, a thermal destruction of the transistor, even at voltages much lower than the specified stationary values. The current rise has to be limited by a small inductance allowing the transistor to consume voltage without exceeding critical field values. >