Temperature in Gunn diodes with inhomogeneous power dissipation

The output power of Gunn oscillators is limited by the increased temperature which affects the velocity-field curve and which may also permanently damage the diode or the metal contacts. The behavior of these oscillators indicates that the dissipation power density is more or less inhomogeneous, depending on the kind of oscillation mode. The present paper makes use of simple models of the dipole domain mode and the accumulation mode in an analysis of the inhomogeneous dissipation power density. The temperature increase caused by this dissipation power is then calculated. The temperature dependence on diode dimensions and mounting is also discussed. It is shown that the temperature is lower when the anode is turned towards the heat sink than when the cathode is turned the same way. This difference amounts to 150°K for an accumulation mode diode with 500°K maximum temperature in the former case.