Doctoral position in theoretical modeling of nanocrystal growth

The Optical Materials Engineering Laboratory (Prof. David J. Norris) in the Department of Mechanical and Process Engineering (D-MAVT) at ETH Zurich investigates the synthesis, growth, structure, and optical properties of semiconductor nanomaterials. Our interdisciplinary and international team combines materials chemistry, optical spectroscopy, electron microscopy, theoretical modeling, and numerical simulation to understand and control materials at the nanoscale.

Project background

Nanometer-scale semiconductor crystallites exhibit optical properties (e.g., absorption and emission spectra) that are strongly dependent on their size. Because this property is useful for creating tunable optical materials for optoelectronic applications ranging from displays and infrared cameras to nanophotonics and quantum technologies, chemical syntheses have been developed that produce nanocrystals from various semiconductors. The most advanced protocols are those that lead to quasi-spherical particles (known as colloidal quantum dots). However, even state-of-the-art nanocrystal samples contain distributions in particle size and morphology that limit their optical performance.

Two classes of semiconductor nanocrystals have been discovered as exceptions to this rule. They display an unusual form of "discrete" growth, jumping between a series of specific sizes. Semiconductor nanoplatelets can be synthesized with atomically uniform thicknesses, while so-called "magic-sized" nanocrystals grow through a sequence of well-defined sizes. These observations suggest that nanocrystals with exceptionally precise dimensions may be possible. Nevertheless, the mechanisms that govern whether nanoplatelets, magic-sized nanocrystals, or conventional colloidal quantum dots form from a specific synthesis remain poorly understood.

The central aim of this project is to develop a universal theoretical framework that explains how these different nanocrystal growth modes emerge. The resulting understanding will be used to guide experiments toward improved control over nanocrystal size, shape, and optical properties.

Job description

The doctoral student will develop theoretical and computational descriptions of the nucleation and growth of semiconductor nanocrystals. The initial focus will be on combining existing models for CdSe nanoplatelets and magic-sized nanocrystals. The work will subsequently be expanded to include conventional, continuously growing quantum dots and other semiconductor materials, including InP.

The project will combine three complementary modeling approaches: First, the student will use density functional theory (DFT) to calculate the energies of surfactant-terminated nanocrystal surfaces, edges, steps, and vertices. These calculations will provide physically meaningful parameters for the growth models. They will also be used to identify surfactant molecules that may stabilize particular nanocrystal shapes. Second, the student will construct mass-balance models describing the coupled growth and dissolution of nanocrystal populations. These models will examine the competitive growth of nanoplatelets and magic-sized nanocrystals by solving systems of coupled rate equations. The results will be compared directly with experimental stability measurements. The models will then be extended to include quantum dots, with the goal of explaining the transition between discrete and continuous nanocrystal growth. Third, the student will use kinetic Monte Carlo simulations to investigate the early stages of nanocrystal growth. Such calculations will examine how initially small crystallites develop into competing morphologies and how growth conditions influence the selection of nanoplatelets, magic-sized nanocrystals, or quantum dots.

The doctoral student will work closely with experimentalists responsible for nanocrystal synthesis and growth studies. This interaction between theory and experiment is central to the project: experimental results will provide input for the models, while simulations will guide the design of new experiments. The calculations will be performed using ETH Zurich’s high-performance computing infrastructure. In addition to research, the doctoral candidate will contribute to general laboratory activities and will have opportunities to participate in teaching and the supervision of bachelor and master’s students.

Profile

We are seeking a curious, motivated, and self-driven candidate with a strong interest in applying theoretical and computational methods to fundamental problems in materials growth. A strong background in thermodynamics, kinetics, statistical mechanics, solid-state physics, physical chemistry, or materials modeling is expected. Applicants must hold, or be close to completing, an MSc degree in chemistry, chemical engineering, mechanical engineering, materials science, physics, computational science, or a closely related discipline. Experience in one or more of the following areas would be advantageous:

• Density functional theory and electronic-structure calculations
• Kinetic Monte Carlo or other stochastic simulation methods
• Numerical solution of coupled differential or rate equations
• Atomistic or mesoscale modeling of materials
• Semiconductor nanocrystals, surfaces, or colloidal growth
• Scientific programming
• High-performance computing

Prior experience with every method used in the project is not required. The successful candidate should, however, have a strong quantitative foundation and an enthusiasm for learning new computational techniques. Academic excellence, a professional approach to research, and the ability to work independently are expected. The candidate must be able to communicate fluently in English, both orally and in writing, and should enjoy working in a collaborative and international research environment.

We offer

We offer a stimulating doctoral project at the interface of theory, computation, and experiment. The successful candidate will join a collaborative and international research group and will receive training in several complementary approaches to materials modeling. The project provides opportunities for external research collaboration, access to advanced computing facilities, interaction with experimental scientists, participation in international conferences, and the supervision of student research projects.

The position is based in the Department of Mechanical and Process Engineering (D-MAVT) at ETH Zurich’s central campus in Zurich, Switzerland. The student will have access to ETH Zurich’s high-performance computing resources. D-MAVT is an interdisciplinary department encompassing mechanical, process, chemical, and biomedical engineering, as well as robotics and control. ETH Zurich offers an outstanding scientific environment with extensive opportunities for collaboration across materials science, chemistry, physics, and engineering.

We value diversity and sustainability

In line with our values, ETH Zurich encourages an inclusive culture. We promote equality of opportunity, value diversity and nurture a working and learning environment in which the rights and dignity of all our staff and students are respected. Visit our Equal Opportunities and Diversity website to find out how we ensure a fair and open environment that allows everyone to grow and flourish. Sustainability is a core value for us – we are consistently working towards a climate-neutral future.

Curious? So are we.

We look forward to receiving your online application with the following documents as a single PDF:

• A cover letter describing your motivation for the position, your relevant research experience, and your principal scientific achievements to date (max. two pages)
• A CV
• Diplomas and course transcripts
• Contact details for at least three academic or professional references

Further information about our laboratory can be found on our Website. Questions regarding the position should be directed to David J. Norris, dnorris@ethz.ch (no applications).

Please note that we exclusively accept applications submitted through our online application portal. Applications via email or postal services will not be considered.

We are recruiting a full-time doctoral candidate to develop theoretical and computational models of semiconductor nanocrystal growth, with an intended starting date on or after October 1, 2026.

The doctoral position is intended for four years at 100% employment and will be supervised by Prof. Dr. David J. Norris. The position is conditional upon admission to the doctoral program at ETH Zurich.