The integrated current sensor now enables the non-reactive measurement of the transistor current for control and short-circuit protection and saves space compared to conventional external current sensors. The integrated temperature sensor enables direct measurement of the temperature of the power transistor and thus maps this thermally critical point much more accurately and quickly than previous external sensors, since the distance and resulting temperature difference between sensor and measuring point is eliminated by the monolithic integration.
"The monolithically integrated GaN power electronics with sensor technology and control thus saves chip space, reduces the effort required for assembly technology and increases reliability. This is crucial for applications in which many small and efficient systems have to be installed in a small space, such as electromobility," says Mönch, who designed the 4 x 3 mm² GaN chip.
For the monolithic integration, the research team uses the semiconductor material gallium nitride, which has been deposited on a silicon substrate (GaN-on-Si). The special feature of GaN-on-Si power electronics lies in the lateral nature of the material: The current flows parallel to the chip surface, whereby all connections are located on the top of the chip and connected via conductor paths. This lateral structure of the GaN components allows the monolithic integration of several components such as transistors, drivers, diodes and sensors on a single chip. A special property of gallium nitride is advantageous over other wide-bandgap semiconductors such as silicon carbide: GaN can be deposited on inexpensive and large-area silicon substrates and is therefore suitable for industrial use.