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Professor Christou and CALCE Research Group Develop Key Advances in Power Electronics--Wide and Ultrawide Bandgap Semiconductor Materials

Over the past 24 months, Professor Christou, and his research group, have developed the highly reliable GaN Heterojunction GaN field effect transistor on both (100) GaN and (111) silicon, which will be applied in microwave transmit-receive modules and in high-voltage and high-power electronics. The results, published by his group during the last 12 months, have made significant impact in developing wide band gap semiconductor device technology--especially in the area of Vertical GaN HEMTs.

Prof. Christou's group has undertaken to resolve the research issues in ultra wide bandgap semiconductor materials (beyond 3.5 eV), including novel transistor structures in diamond heterostructures. The goal of the present research is to achieve fundamental, experimental, and theoretical advances toward understanding the radiation interactions with two-dimensional conducting channels in diamond-based semiconductor structures. The group is investigating high field effects, such as hot carriers and hot phonon generation, the material/interface defects, surface and interface states, as well as the materials science processes, which occur at ohmic contacts and Schottky barriers.

This research will help effectively parameterize the degradation mechanism in diamond structures due to radiation fields.

Prof. Christou's team uses specifically designed test structures and field effect transistors (FETs) fabricated at CALCE and the University of Maryland's Nanofabrication Center. The enhanced device performance is achieved using two-dimensional diamond-surface conduction and buried 'delta'-doped layers. It will be based on the team's recent success in growing boron delta-doped single-crystal diamond structures with the highest in the world hole mobility that exceeds published results to date. Ultimately, the physics-based radiation degradation mechanisms will be identified and assessed at University of Maryland's Radiation Facilities.

Prof. Christou and his graduate students conduct research in Wide Band gap semiconductor materials for Power Electronics. His research in Power Electronics Materials, devices and systems encompasses manufacturing and process science, extreme environments, and radiation effects in energy materials and devices. The group has also made significant contributions in photonic materials and devices, optoelectronic device, component reliability, and flexible devices and materials for flexible displays. The research emphasizes developing graphene interconnects for flexible electronics and investigating the mechanical, optical, and electrical properties of graphene on polymer substrates.

For more information, contact Prof. Aris Christou.

The Center for Advanced Life Cycle Engineering (CALCE), the largest electronic products and systems research center focused on electronics reliability, is dedicated to providing a knowledge and resource base to support the development of competitive electronic components, products, and systems.

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