Power Electronics Department

The Power Electronics Department researches, develops, and provides tools for power electronic device development. This includes dynamic device characterization techniques, various simulation possibilities including physical, thermal, and mechanical device simulation as well as life-time testing.

  • Simulation of electric field distribution
    [+] Simulation of electric field distribution in GaN power switching transistor at off-state
  • Test facility for microwave lifetime characterization
    [+] Test facility for microwave lifetime characterization
  • Close-up of microwave test fixture
    [+] Close-up of microwave test fixture for thermally activated lifetime tests at 1.7 GHz and power-matched load conditions
  • Test fixtures for thermally activated DC lifetime testing
    [+] Test fixtures for thermally activated DC lifetime testing up to 200°C base-plate temperature

Device simulation

Device simulation is an indispensable tool throughout the value-added chain of device development. It offers the capability to predict device performance and thus cuts down test sequences in the cleanroom in order to engineer devices according to certain specifications. Furthermore, simulation tools are indispensable for gaining a better physical understanding of the devices, especially with regard to drift and reliability effects.

Power device development gets routinely supported by following simulation capabilities:

  • Physical device simulation (Sivaco Atlas)
  • Thermal and mechanical device simulation (Ansys)

Device characterization

Power switching devices require ambient dynamic characterization possibilities in order to trace mechanisms that might compromise efficiency when the device is operated in real system environment. For this sake, different possibilities of dynamic on-state resistance characterization have been implemented and also been developed from scratch. Dynamic characterizations, especially in connection with inductive loads, are performed at Technische Universität Berlin in frame of our Joint Lab Power Electronics.

Device characterization also includes measurements of heat distribution across extended power transistors and the determination of thermal impedances.

Reliability evaluation

Reliability tests on GaN microwave and power electronic devices are routinely performed. As the devices are quite different in design of course the applied test routines also deviate from each other. For microwave power devices a well-established test sequence has been elaborated consisting of the following subsequently carried out test routines:

  • Device pre-selection according to DC-tests
  • Step-wise increase of stress conditions until device degradation
  • DC and RF reliability tests at different channel temperatures and different biasing conditions, extrapolation of MTTF

Details on reliability test equipment:

  • On-wafer measurement setup for fast robustness tests
  • Long-term DC reliability test systems for performing reliability measurements with combined thermal and electrical stress of up to 142 devices at a base plate temperature of up to 200°C, up to 1100 V drain bias, and up to 50 W dissipated power per device
  • Microwave reliability measurement setup (L-band, 1.7 GHz, power-matched to 50 Ω) for eight devices simultaneously with up to 200 W dissipation power per device