High-Voltage Characterization of Semiconductor Power Devices in Controlled Environments

Principal Investigator: Rongming Chu, Th Pennsylvania State UniversityProgram Manager: Mr. Lynn J. Petersen, Office of Naval Research (Code 331)Wide bandgap semiconductors (WBG), e.g., SiC and GaN, have demonstrated superior performance for below 1 kV applications. Scaling SiC and GaN devices to higher voltages (1~35 kV) will lead to more efficient and more compact shipboard electrical systems. Critical challenges for scaling the voltage rating of the conventional WBG 1D unipolar power devices to medium voltage regime include: (1) form a thick enough drift layer to hold the standoff voltage; (2) accurately control the doping in the drift layer to allow on-state conduction while maintaining off-state blocking; and (3) manage the E-field in the drift layer.For Si power MOSFETs, scaling the voltage from sub-100-V to 600~900 V was achieved by deploying the advanced superjunction design. Similarly, WBG superjunction has the potential to scale the voltage from today#s sub-1-kV range to over10 kV. Development of SiC superjunction MOSFETs is on-going. Various GaN superjunction designs have been proposed, promising higher performance than the SiC superjunction devices at lower cost. The PI#s group has recently demonstrated that the charge balanced GaN super-heterojunction structure can support a blocking voltage as high as 12.5 kV, simultaneously with low on-resistance and minimal trapping effects. This project will support the characterization of high-voltage devices under controlled environments: pressure and temperature.Characterization under controlled environments is important for understanding breakdown mechanisms of wide bandgap semiconductor devices and structures. Temperature-dependent breakdown measurements are often used to determine the role of phonon scattering in the avalanche breakdown process. Pressure-dependent breakdown measurements are needed to understand the partial discharge of dielectrics in the device structure.Characterization under controlled environments is also important for evaluating the capability of devices under harsh environments. Some DoD applications desire the capability of operating electronics, including power devices, at elevated temperatures. Some DoD applications also require the operation of power electronics under reduced air pressure, where the partial discharge problem becomes more significant.Publicly Releasable