Nick Pant
My name is Aagnik; I go by both Aagnik and Nick. I am a computational materials physicist, currently developing methods to understand electron-phonon interactions in semiconductors from first principles. During my Ph.D., I developed and applied first-principles and multi-scale quantum methods to understand the performance limitations of nitride semiconductors for LEDs and power electronics. I am a recipient of the NSERC Postgraduate Scholarship and the MICDE Graduate Fellowship.
Univ. of Texas at Austin (Postdoc, Physics) ← Univ. of Michigan (Ph.D., Applied Physics) ← McGill Univ. (B.Eng., Electrical Engineering)
Research Highlights
Challenging the conventional view on what makes LEDs efficient
By developing a theoretical framework to assess the impact of disorder on optoelectronic materials, I have challenged a long-standing hypothesis that carrier localization is responsible for the highly efficient nature of nitride LEDs. The takeaway is simple: designs that minimize the defect density acheive high efficiency. (Phys. Rev. Applied 20, 064049 (2023))
Uncovering the origin of the unwanted hue shift of nitride LEDs
Using multi-scale modelling, I identified the detrimental role of degenerate carrier densities in causing the notorious hue-shift problem of nitride LEDs, where a green LED undesirably becomes blue with increasing current. I also showed that quantitative agreement with experiments requires considering many-body effects that are ignored by most commercial solvers. (AIP Advances 12, 125020 (2022))
Theoretical prediction of AlN/GaN superlattices for power electronics
Using state-of-the-art density-functional theory and many-body perturbation theory, I have predicted that atomically thin superlattices of AlN and GaN are the most promising technologically viable semiconductors for power devices, based on the modified Balifa figure of merit, because of their ultra-wide band gaps and high electron mobility. Such superlattices can be grown with MBE or MOVPE. (Appl. Phys. Lett. 121, 032105 (2022))
Developing first-principles techniques to study alloy scattering in AlGaN
I have developed a computational method to calcualte alloy scattering in semiconductors from first principles; using this technique, I found that alloy scattering is an important energy-loss mechanism in AlGaN alloys, which have applications in UV LEDs and power electronics, limiting their carrier transport properties. (Appl. Phys. Lett. 117, 242105 (2020))
Updates
I have several exciting talks comping up in 2024: one invited talk at Photonics West on the simulation of LED materials and another invited talk at a workshop on Disorder in Semiconductor Physics and Devices at UCSB. I am also giving a talk in the MRS Spring meeting (EL04) on fresh findings on Auger-Meitner recombination in AlGaN UV LEDs.
As part of a fruitful collaboration with industry (Lumileds) and the experimental group of Prof. Danny Feezell at UNM, I helped show that green LEDs exhibit lower internal quantum efficiency than blue LEDs because polarization fields increase the operating carrier density and promote Auger-Meitner recombination (Appl. Phys. Lett. 122, 212108 (2023)).
I presented a talk at the 2022 International Workshop on Nitride Semiconductors in Berlin, challenging the notion that carrier localization gives rise to defect tolerance in InGaN LEDs. I also presented a poster on my recent work modelling the optical spectra of LEDs.
I presented my findings on atomically thin superlattices of AlN/GaN for power electronics in the MRS Spring 2022 meeting.
I have written an invited review on theoretical methods for characterizing and predicting ultra-wide-band-gap semiconductors; I co-wrote the sections on low-field transport and carrier mobility as well as radiative and non-radiative recombination (J. Mat. Res. 36, 4616 (2021)).
A little more about me
I develop and apply quantum methods to study mechanisms that limit the performance of semiconductor devices. My speciality is in connecting predictive first-principles approaches designed to study the microscopic properties of materials with macroscopic device properties. I am motivated by problems that address the grand challenge of improving the energy efficiency of semiconductor devices that run our lives. My research journey began as an experimentalist in the group of Zetian Mi, where I grew semiconductor crystals with Molecular Beam Epitaxy to build nitride-semiconductor photocatalysts that produced clean chemical fuels with sunlight. I turned to theory to understand the microscopic energy-loss mechanisms in semiconductors that were challenging to study experimentally because they did not have a clear signature. This journey led me to collaborate with industry (Lumileds) and experimental groups (Feezell group at UNM and Rajan group at OSU) as well as theory groups (Van de Walle group at UCSB) to uncover the microscopic loss mechanisms in nitride LEDs.
I was born in Kathmandu, Nepal and I immigrated to North America when I was ten years old (I grew up mostly in Canada, and have lived in nine different cities across the world). As an immigrant, I understand that our socioeconomic backgrounds touch every aspect of our lives. It is because of this that I strongly believe in efforts to promote diversity and equity. One concrete example I look to for inspiration is the success of the Applied Physics program at the University of Michigan in promoting diversity. In terms of hobbies, I enjoy cycling, hiking, and travelling the world, and I am a big fan of languages and linguistics. In addition to English, I speak Nepali, and a little bit of Hindi and French. My favourite movie is Timecrimes, an independent and underrated Spanish movie that is hilarious and bound to give you some great laughs.