Ph.D., Friedrich-Alexander-University Erlangen-Nuremberg, Germany
Materials Science

M.S., Friedrich-Alexander-University Erlangen-Nuremberg, Germany
Physics and Physical Chemistry

Vapor growth of compound semiconductors (SiC, GaN, AlN)

· Development of wide bandgap substrates for high power and high frequency semiconductor devices and optoelectronic applications by PVT (Physical Vapor Transport) and HVPE (Hydride Vapor Phase Epitaxy) (demonstrated several world records of low defect densities in SiC substrates; developed 1st high purity semi-insulating 4H-SiC substrate)

· Simulation of heat and mass transfer for PVT and HVPE processes; Evaluation of the thermoelastic stress during growth

· Process implementation and control on an industrial scale (responsible for the process transfer from R&D to volume production for the fabrication of commercial wafer products, supporting a ~ 400 million dollar/year semiconductor device business)

Characterization of compound semiconductors

· Point defects: electrical and optical properties, many body effects, compensation mechanisms, thermal conductivity (Experience with the following characterization techniques: Hall-effect, CV, DLTS, EPR, [time dependent-] low temperature photoluminescence, optical absorption etc.); Significant contributions to clarify the fundamental role of intrinsic defects in the compensation mechanism in high purity semiinsulating SiC

· Dislocations: structure and generation mechanisms, effect on semiconductor device properties (Experience with the following characterization techniques: Synchrotron White Beam X-ray Topography, AFM, Stress Birefringence, Optical Emission Microscopy, Etching etc.)

Influence of material properties on semiconductor device performance

· Degradation mechanisms of high power and high frequency devices (Significant contributions to eliminate the Vf-Drift in SiC p-i-n diodes)

· Trapping effects in high frequency devices (Significant contributions to eliminate back-gating and trapping in SiC MESFETs)

Theoretical work on the physical properties of compound semiconductors

· Carrier mobility / scattering mechanisms, hopping

· Thermal conductivity

· Metal-Insulator Transition (MIT)

· Impurity bands in semiconductors (Efros-Model, Wigner crystallization)