We have demonstrated the performance of circuits on stainless steel and compared them to those fabricated on quartz substrates. We have modeled the substrate dependence of the minimum and maximum operating frequency of a Shift Register, and found close agreement with our experimental measurements. This model can be used as a design guideline for future development of circuits on conducting substrates.

Low resistance n+GaN contact materials were experimentally studied for GaN HEMT applications by selective area epitaxy regrowth on a patterned SiC substrate. Epitaxy was performed by metal organic chemical vapor deposition using 100% H2 or 100% N2 as the carrier gas. Thin film characterization demonstrated that n+GaN grown in N2 carrier gas has a superior morphology with improved crystalline quality to that grown in H2 carrier gas. The results also indicated that the surface morphology of n+GaN grown in N2 carrier gas is less sensitive to mask pattern density and micro-loading effects with Si doping concentrations up to 1 × 1020/cm3. Secondary ion mass spectrometry analysis shows that C and O impurity levels in n+GaN are one order of magnitude lower with N2 carrier gas than with H2. The electrical measurement of transmission line model structures shows an n+GaN sheet resistance of 15 Ω/sq and an Ohmic metal to n+GaN contact resistance of 0.02 Ω-mm for structures grown in N2 carrier gas. These values represent 7.1× and 2.5× improvements compared to H2 carrier gas.

For the first time, large area 10 kV SiC power devices are being produced capable of yielding power modules for high-frequency megawatt power conversion. To this end, the switching performance and power dissipation of silicon carbide (SiC) n-channel IGBTs and MOSFETs are evaluated using numerical simulations software over an extended current range to determine the best device suitable for 10 kV applications. Each device is also optimized for minimal forward voltage drop in the on-state.