Topological Superconductivity

Topological superconductors (TSC) combine macroscopic quantum coherence with topological protection. They enable robust quantum states that are naturally resilient against disorder and material imperfections. How can topological superconductivity be identified unambiguously in transport experiments? Unlike topological insulators, where metallic edge states can be detected directly because the bulk is insulating, topological superconductors present a more complex situation: topological states coexist with, and are often masked, a superconducting bulk. Several related questions remain open, such as the role of spin in topological superconductivity and how to quantify the associated magnetization of a spin-polarized condensate.

My research has been built around these questions. Using hBN-encapsulated mesoscopic Fe(Te,Se) rings and low-noise measurements, we developed a transport platform to probe non-trivial phase winnding and spin-polarization of topological superconducting states. We provide evidence for half-integer winding of the order parameter and found signatures of intrinsic magnetization of the condensate. Read more

Preprints:

arXiv:2505.01522

arXiv:2508.05030

arXiv:2603.08891

CMOS-compatible devices based on 2D materials

2D materials such as graphene are especially attractive for semiconductor photovoltaics optoelectronics. Unlike conventional Schottky junctions, where the metal blocks a significant fraction of the incident light, graphene junctions allow efficient light absorption in the semiconductor. Graphene–semiconductor junctions are also physically attractive because they represent a hybrid 2D/3D interface. How does the 2D nature of graphene affect charge injection into a 3D semiconductor? What limits carrier injection through a graphene–silicon Schottky junction and what is the maximum PV conversion efficiency limit?

Our experiments showed that carrier transfer across graphene–silicon junctions is fundamentally constrained by the out-of-plane velocity of carriers in graphene, resulting in a transfer velocity many orders of magnitude smaller than that of conventional Au–Si Schottky junctions. We further showed that increasing the number of assembled graphene layers strongly modifies the reverse saturation current.

While most two-dimensional materials are semiconductors or Dirac semimetals, truly metallic 2D materials remain far less developed. This gap raises an important concern regarding metallic interconnects for 2D electronics. In related work, we demonstrated chemical vapor deposition growth of atomic-thickness borophene using diborane pyrolysis, establishing a scalable pathway toward 2D metallic films for electronic interconnects.

Selected publications:

Advanced Optical Materials 7, 1900470, (2019) 

Applied Physics Letters 117, 053902, (2020) 

Physical Review Applied 14, 064048, (2020)

ACS Applied Materials & Interfaces 13(7), 8844-8850, (2021)

Hybrid organic-inorganic optoelectronic devices

Hybrid organic–inorganic junctions offer a practical route for integrating organic semiconductors with mature silicon technology. PEDOT:PSS/silicon heterojunctions are particularly attractive because they can be fabricated through a low-temperature, solution-based process, making them suitable for large-are monolithic optoelectronic devices. The transparent and conductive organic layer allows efficient light absorption in silicon, while interfacial band bending forms an ultrashallow depletion region that supports carrier separation.

My work in this area focused on the physics and device performance of PEDOT:PSS/silicon heterojunctions. We showed that reverse-bias transport is governed by injection over a quasi-Schottky barrier at the interface, while forward-bias transport is dominated by space-charge-limited conduction through the organic layer. We also demonstrated large-area hybrid position-sensitive detectors with high lateral photovoltage sensitivity. Extending the same platform to photodiodes, we achieved ultrahigh photovoltage responsivity, pW-level noise-equivalent power, and stable self-powered operation after long-term air exposure. Together, these studies established hybrid organic-inorganic heterojunctions as a scalable and low-cost platform for monolithic optoelectronic sensors.

Selected publications:

Applied Physics Letters 112, 113302, (2018) [Editor’s Pick]

Physical Review Applied 12, 034002, (2019)

Applied Physics Letters 117, 073301, (2020)

Solar cells and physical modeling

During my master and early PhD, I worked on fabrication and characterization of photovoltaic solar cells. I also worked on modeling and simulation of physical phenomena across different material systems, with an emphasis on charge transport, nanoscale morphology, and plasma–solid interactions. 

Using Monte Carlo random-walk simulations, I studied electron transport in porous networks of wide band-gap semiconductors and showed that structural confinement can enhance directional diffusion, suggesting a route to improved internal quantum efficiency of nanostructured solar cells. Motivated by these results, we fabricated dye-sensitized solar cells with columnar structure and measured carrier lifetime, diffusion length, and converion efficiency. In related work, I modeled plasma-enhanced CVD growth of carbon nanotubes by combining COMSOL multiphysics simulations with numerical calculations of dielectrophoretic forces, which succesfully explained the growth of self-organized single-standing carbon nanotubes. 

These studies reflect my early experience in PV solar cells and computational modeling and using numerical methods to connect microscopic mechanisms to macroscopic material and device behavior.

Selected publications:

Journal of Applied Physics 118, 064304, (2015)

Journal of Applied Physics 119, 114302, (2016)

Solar Energy 133, 549, (2016)

ChemPhysChem 17, 3542, (2016)

Journal of Nanoparticle Research 19, 17, (2017)