Peter H. Jacobse

I am Peter Jacobse, a postdoctoral researcher at the University of California, Berkeley in the group of Michael F. Crommie. My research focuses on designing, building and analyzing carbon-based nanostructures on surfaces. Essentially, I am an architect, but my building blocks are atoms and chemical bonds instead of bricks and steel. I use chemical reactions instead of concrete to assemble the structures that I am interested in. Then, I zoom in on the new quantum mechanical properties that they exhibit. The nanostructures that I make are of interest for use in faster, smaller, smarter and more energy-efficient nanoelectronics, including spintronics and quantum computing.

One of my favorite materials is graphene nanoribbons - narrow strips of the wonder material graphene - which are excellent conductors of electricity. Although carbon is still a long way away from rivaling silicon, we can now make functional graphene nanoribbons that work as metals, semiconductors, transistors, resonant tunneling diodes, sensors, and more. Better yet, we are developing strategies to engineer electron spin and magnetism in nanoribbons and carbon-based lattices. Magnetism and spin are important ingredients for data storage, spintronics (a greener, more energy-efficient alternative to electronics) and quantum computing. I am convinced that carbon will become a serious contender to silicon in some applications where silicon-based technologies will soon hit a limit. Carbon is uniquely tunable and versatile in a way that silicon is not, and ultimately carbon-based electronics will be able to operate at lower power consumption and higher data processing density than silicon.

I have personally been at the forefront of the development of techniques to improve the synthetic capabilities of carbon-based nanostructures. For example, I have pioneered matrix-assisted direct transfer, an important technique to bring polymers and macromolecules onto the surface and turn them into graphene nanoribbons, after they have been prepared by chemists. This allows me to study these molecules on the surface using scanning tunneling microscopy (STM). In addition, I have been at the forefront of turning carbon-based nanomaterials into actual devices that function as real transistors, and I have made steps in making new kinds of structures with different electronic properties.

My work combines insights from synthetic organic chemistry, theoretical and experimental physics, surface science, nanoscience and device engineering. As such, I fulfill a very interesting, interdisciplinary role in academia, where I collaborate with chemists, theoretical and experimental physicist and engineers. I am in the unique position where one moment, I talk about coupling reactions, then the next moment I talk about Fermi surfaces, and then about subthreshold swings - concepts from vastly different fields that all converge in my research. In fact, I have even ventured into these fields myself, as I have performed synthetic organic chemistry, in the fume hood, but have also developed a Mathematica package for quantum mechanical (tight-binding and mean-field Hubbard) calculations. I am passionate about my interdisciplinary research, my role as collaborator and interpreter between all these different people and perspectives, the enthusiasm that my chemistry collaborators express when I look at their molecules and structures under the STM, the joy that the theoreticians express when I finally make their models come to life, and my role as someone who is pushing the boundaries of carbon nanomaterials.

Among my scientific achievements are the fabrication of nanoporous graphene (transistors) as well as new types of electronically functional graphene nanoribbon heterostructures and quantum dots. I have experimentally revealed the phenomenon of negative differential resistance in graphene nanoribbons. I have made and studied graphene nanoribbons with four-membered rings and five-membered rings, as well as magnetic nanoribbons. I am a leading expert on nitrogen doping in graphene nanoribbons. I have provided fundamental insights into the mechanisms of on-surface chemistry reactions through my work utilizing noncontact-AFM and x-ray photoelectron spectroscopy (XPS). I am an expert in graphene nanoribbon transport through my work on in-situ lifting/transport measurements and transport calculations. I have developed a software package for performing electronic structure calculations at the level of tight-binding/mean field Hubbard theory, called MathemaTB. I have developed new surface-synthesis techniques such as matrix-assisted direct (MAD) transfer, which vastly increased the scope of nanostructures accessible on surface. I have used MAD transfer in conjunction with protecting-group aided iterative synthesis (PAIS) to achieve, for the first time, the fabrication of fully monodisperse graphene nanoribbons with precisely predetermined length and monomer sequence.