Dr. Hanif Mohammadi

Introduction

My name is Hanif Mohammadi, and I hold the position of project manager and Wissenschaftlicher Mitarbeiter at Institut für Nanostrukturtechnologie und Analytik (INA), Universität Kassel, Germany. With a strong background in material science and engineering research, I have dedicated over 8 years to the field of Nano Technology and Quantum Physics. Throughout my career, I have been recognized for my innovative thinking and expertise in designing and executing experiments. A proven track record highlights my ability to enhance the performance of optoelectronic devices using diverse preparation and passivation methods. My true passion lies in engaging with challenging and forward-thinking subjects within the laboratory, where I can leverage my expertise in rigorous experimental work.

Teaching Duties

Lecture assistant

Thermal properties of nanostructured materials
Low-dimensional electronic systems
Nanostructured photonic systems and optical resonators
Fabrication and characterization methods

Project Management

OASIS

Optically Active Silicon-Based Nanostructured III-V Compound

Patent

Itaru Kamiya and Hanif Mohammadi,

“Semiconductor devices and their preparation methods”

One Portal Dossier (OPD) Patent Application No.: 2023005146 (JP 2023-005146)

Publication

Hanif Mohammadi, et al.,

“Atomic layer deposition of diethylzinc/zinc oxide on InAs surface quantum dots: Self-clean-up and passivation processes,”

Applied Surface Science 612 (2023) 155790.

Hanif Mohammadi, et al.,

“Passivation capping of InAs surface quantum dots by TMA/Al2O3: PL enhancement and blueshift suppression,”

Journal of Applied Physics133 (2023) 185303.

Hanif Mohammadi, et al.,

“Anomalous photoluminescence of InAs surface quantum dots: intensity enhancement and strain control by underlying quantum dots,”

Nanotechnology 33 (2022) 415204.

Hanif Mohammadi, et al.,

“Synthesis Photocatalytic TiO2/ZnO Nanocomposite and Investigation through Anatase, Wurtzite and ZnTiO3 Phases Antibacterial Behaviors,”

Journal of Nano Research 51 (2018) 69.

Hanif Mohammadi, et al.,

“Novel Passivation Method of InAs Surface Quantum Dots: Near Nondestructive Diethylzinc Atomic Layer Deposition,”

SSRN 4948296.

Hanif Mohammadi, et al.,

“Unraveling the Impact of Trimethylaluminum in the Nondestructive Passivation of InAs Surface Quantum Dots,”

SSRN 4948298.

Skills

Semiconductor Thin-film growth

Molecular Beam Epitaxy (MBE)

MBE involves the precise growth of crystal structures by using molecular beam of the elements. The growth occurs in an epitaxial manner, meaning the deposited layers maintain the same crystal structure as the underlying substrate.

I have gained extensive experience in utilizing MBE for epitaxial growth of Group III-V materials, with a particular focus on InAs quantum dots. Throughout my studies, I have actively engaged in critical maintenance tasks for the ultra-high vacuum chamber and its pumps, ensuring their optimal performance. By consistently maintaining the equipment, I have upheld the necessary conditions for precise and controlled deposition processes, contributing to the successful growth of high-quality materials.

Atomic Layer Deposition (ALD)

ALD is based on a sequential, self-limiting reaction process that enables precise atomic control over layer thickness and composition. The reaction between the precursor and the substrate surface reaches saturation, resulting in the formation of a single atomic layer.

I have extensive experience in utilizing Plasma-Enhanced ALD (PE-ALD) for the preparation of aluminum oxide, zinc oxide, gallium oxide, and silicon oxide thin layers. Through my work, I have gained valuable expertise in controlling and manipulating the ALD chemical reactions to effectively passivate surface quantum dots. This involves precise tuning of process parameters to achieve optimal surface passivation, enhancing the performance and stability of quantum dot-based devices.

Microscopy

Atomic Force Microscopy (AFM)

AFM technique allows me to observe and characterize of InAs surface quantum dots at the nanoscale revealing the topography and structural details of the quantum dots. By scanning the sharp tip of the AFM probe across the sample surface, the interaction forces between the tip and the quantum dots caused deflections in the cantilever, which were used to generate a topographic image of quantum structures.

Scanning Electron Microscopy (SEM)

SEM employs a focused electron beam that scans across the sample surface allows me to observe and analyze InAs surface quantum dots. When the electron beam interacts with the InAs surface, several signals are generated, including secondary electrons, backscattered electrons, and characteristic X-rays. These signals are then detected and used to generate an image of the sample. The high-resolution imaging capabilities allowed me to visualize of the quantum dot morphology, size, and distribution.

Transmission Electron Microscopy (TEM)

TEM involves transmitting a high-energy electron beam through an ultra-thin specimen, such as the InAs quantum dots and their surrounding layers, which provides valuable information about the sample's structure, morphology, and composition. TEM also provides insights into the crystal lattice structure and defects within the quantum dots and enabled the examination of the wetting layer and capping layers surrounding the InAs quantum dots, which have a significant impact on the behavior and properties of the quantum dots.

Focused Ion Beam (FIB)

FIB technology plays a pivotal role in materials science, offering meticulous preparation of samples for TEM. Specifically, in the intricate world of materials science, FIB finds extensive application in the precise sectioning of InAs Quantum dots grown on a GaAs layer. This precision is essential for facilitating their detailed examination through TEM techniques. The standout feature of FIB lies in its extraordinary nanometer-scale resolution, enabling the exact and precise cutting necessary for the preparation of quantum dot samples for TEM cross-sectional imaging.

Axis pro (micro sampling equipment)

Axis Pro stands as a pinnacle in micro-sampling equipment, handling quantum dot samples prepared by FIB technology. This fully covered, all-in-one micro-sampling marvel seamlessly transfers cut quantum dot samples onto the grid, prepping them for in-depth cross-sectional imaging. Axis Pro is compatible with a multitude of analytical methods, ranging from TEM and SEM, offering researchers an unparalleled tool for a wide array of scientific explorations.

X-ray Spectroscopy

X-ray Photoelectron Spectroscopy (XPS)

XPS enabled me to analyze of the reduction of native oxide on InAs surface quantum dots by comparing the elemental composition before and after ALD passivation. It allows quantify the changes abundance of different elements, including the reduction in oxygen content and assess the effectiveness of the passivation in reducing the native oxide layer.

Energy Dispersive X-ray Spectroscopy (EDX)

EDX performed inside a SEM involves the irradiation of a sample with X-rays, causing the emission of photoelectrons from the sample surface, which carry information about the elemental composition and chemical bonding states of the sample. This enables me to analyze and map the InAs surface quantum dots and their cap composition.

Grazing Incidence X-ray (GIXRD)

GIXRD allowed me to analyze of the cap layers on InAs quantum dots to obtain information about the thickness and crystallographic structure of the cap layers. By analyzing the peak positions, intensities, and shapes, I could extract crystallographic information such as lattice constants, crystal quality, and strain in the cap layers.

Simulation

Nextnano simulation software

Wave function calculation

Nextnano enabled me to simulate the wave functions of electrons and holes within InAs quantum dots by solving the Schrödinger equation numerically. This allows for the determination of the electronic properties of InAs quantum dots, including energy levels, charge distribution, and density of states. These properties are crucial for understanding phenomena such as quantum confinement, carrier dynamics, and optical properties of the quantum dots.

Strain and relaxation calculation

By using Nextnano, I have calculated the strain in InAs quantum dots which quantifies the deformation of the crystal lattice within the quantum dots. The strain simulation in Nextnano provides information about the magnitude and distribution of strain within the quantum dots. This data can be used to analyze the impact of strain on the energy levels, band structure, and carrier confinement within the dots. It also helps in understanding the strain-induced modifications of the electronic and optical properties of the quantum dots. By adjusting various parameters, such as dot size, composition, or substrate choice, Nextnano allows for the exploration of different strain configurations and their effects on the quantum dot properties. This enables the optimization of strain engineering strategies for tailoring the electronic and optical characteristics of InAs surface quantum dots.

Band edge calculation

By using Nextnano, I have calculated the band edge of InAs quantum dots which allows for the determination of energy levels and wave functions associated with the conduction and valence bands of the InAs quantum dots. The results of the band edge calculation provide valuable insights into the energy spectrum of the quantum dots. This includes the determination of energy levels, bandgap, and the density of states within the quantum dots. By analyzing the band edge properties, I have gained gain a better understanding of the electronic behavior and optical properties of InAs quantum dots.

Optics

Photoluminescence (PL) Spectroscopy

PL analysis enabled me to study the optical properties of InAs quantum dots. The PL spectrum provides insights into the energy levels, band structure, and radiative recombination processes within the InAs quantum dots. PL analysis offers several key pieces of information for example it provides the emission wavelength and the quantum dot's emission efficiency.

Latest News

March 2025: Poster CINSaT, Kassel university.

S. Hagag, H. Mohammadi, et al.,

“Fine-Tuning GaAs Island Growth Parameters on Silicon (100) Substrate: Advancing Towards Optically Active Silicon-Based III-V Nanostructures,”

The 2025 CINSaT, 24P,March 13, 2025.

October 2024: I have start my new position as a postdoctoral fellow at Kassel University, Institute for Nanostructure Technology and Analytics (INA), Technical Physics, Germany.

October 2024: Poster smart energy symposium, Toyota Technological Institute.

H. Mohammadi, et al.,

“Chemical Sensors through Wavefunction Manipulation of InAs Surface Quantum Dots,”

The 16th smart energy symposium, TTI-9, October 18, 2024.

September 2024: Poster presentation of my novel findings in ICMBE.

H. Mohammadi, et al.,

“Wavefunction Manipulation of InAs Surface Quantum Dots via Growth Parameter Adjustment: A Promising Approach for Enhanced Sensing,”

The 23th international conference of molecular beam epitaxy (ICMBE), TH-PS-36, September 12, 2024.

September 2024: Oral presentation of my novel findings in ICMBE.

H. Mohammadi, et al.,

“Metal Oxide Capping of InAs Surface Quantum Dots by Atomic Layer Deposition: An Alternative Approach to MBE Capping,”

The 23th international conference of molecular beam epitaxy (ICMBE), TU-B2-02, September 10, 2024.

September 2024: Oral presentation of my novel findings in ICMBE.

H. Mohammadi, et al.,

“InAs Surface Quantum Dot Passivation with Self-Clean-Up: Diethylzinc vs. Trimethylaluminum for Atomic Layer Deposition,”

The 23th international conference of molecular beam epitaxy (ICMBE), MO-A4-05, September 9, 2024.

March 2024: Oral presentation of my novel findings in Japanese Society of Applied Physics.

H. Mohammadi, et al.,

“Fine tuning of InAs quantum dot growth parameters for high areal coverage and density,”

The 71th JSAP Spring Meeting, 24a-22A-7, March 22-25, 2024.

October 2023: Poster smart energy symposium, Toyota Technological Institute

H. Mohammadi, et al,

“Non-destructive capping of quantum dots for energy devises: Cross-sectional analysis,”

The 15th smart energy symposium, TTI-5, October 19, 2023.

Sep 2023: Oral presentation and poster international conference on solid state devices and materials

H. Mohammadi, et al,

“Unveiling the role of trimethylaluminum in passivating InAs surface quantum dots,”

The 55th SSDM meeting, SO-PS-11-18, September 5-8, 2023.

Hanif Mohammadi international conference

July 2023: I have start my new position as a postdoctoral fellow at Toyota Technological Institute.

July 2023: I have received my Ph.D. degree from Toyota Technological Institute in Ultimate Material.

On a radiant summer day that emerged amidst the gloomy clouds of the rainy season, I triumphantly conquered a formidable challenge. I proudly accomplished my ultimate academic pursuit, attaining a distinguished Ph.D. degree in the remarkable field of Ultimate Materials, with a profound focus on the captivating realm of quantum physics. I had the privilege of being mentored by Professor Hiroyuki Sakaki, who in 1982, introduced the concept of nano-scaled three-dimensional semiconductors with high confinement, which he called "quantum box." Under the guidance of Professor Itaru Kamiya, I had the opportunity to contribute to the research and development of "Quantum Dots" as the second generation of scientists that continued the legacy of Professor Sakaki.

June 2023: Our founding got patented

I. Kamiya, H. Mohammadi, “Semiconductor devices and their preparation methods,”

Application No: JP 2023-005146

June 2023: I have successfully defended my PhD summa cum laude.

May 2023: Publication of my studies in Journal of Applied Physics.

March 2023: Oral presentation of my novel findings in Japanese Society of Applied Physics.

H. Mohammadi, et al,

“Diethylzinc passivation of InAs surface quantum dots,”

The 70th JSAP Spring Meeting, 15p-D411-11, March 15-18, 2023.

March 2023: Publication of my studies in Applied Surface Science.

October 2022: Poster smart energy symposium, Toyota Technological Institute

H. Mohammadi, et al,

“Metal-oxide passivation of InAs surface quantum dots for energy devices,”

The 14th smart energy symposium, TTI-16, October 6, 2022.

Oct 2022: I have start my new position as a research assistances at Toyota Technological Institute.

September 2022: Oral presentation of my novel findings in Japanese Society of Applied Physics.

H. Mohammadi, et al,

“PL enhancement of InAs surface quantum dots by ex situ DEZ/ZnO passivation/capping,”

The 83rd JSAP Autumn Meeting, 20p-C401-6, Sep 20-23, 2022.

July 2022: Publication of my studies in “Nanotechnology” journal.

March 2022: Oral presentation of my novel findings in Japanese Society of Applied Physics.

H. Mohammadi, et al,

“Photoluminescence enhancement of InAs surface quantum dots by Al2O3 passivation,”

The 69th JSAP Spring Meeting, 22p-D316-10, March 22-26, 2022.

September 2021: Oral presentation of my novel findings in Japanese Society of Applied Physics.

H. Mohammadi, et al,

“Long wavelength PL of InAs surface quantum dots enhanced by underlying reservoir,”

The 82nd JSAP Autumn Meeting, 10p-N303-14, September 10-13, 2021.

March 2020: Oral presentation of my novel findings in Japanese Society of Applied Physics.

H. Mohammadi, et al.,

“Novel InAs SK/SML/SK quantum dot structures and steps toward new broadband IR detectors,”

The 67th JSAP Spring Meeting, 12a-D511-8, March 12-15, 2020.

October 2019: Strat my PhD study at Toyota Technological Institute

February 2018: Publication of my studies in Journal of Nano Research.

January 2015: Received my master degree in Nanotechnology with GPA 3.6.

Honors and Services

ad hoc reviewer:

Applied Surface Science (Appl. Surf. Sci.)
Materials Science in Semiconductor Processing (Mater. Sci. Semicond. Process.)
Surface & Coatings Technology (Surf. Coat. Technol.)
Journal of Crystal Growth (J. Cryst. Growth)
Optical Materials (Opt. Mater. Express)
Journal of Nano Research (JNanoR)
Nano Hybrids and Composites (NHC)
Journal of Metastable and Nanocrystalline Materials (JMNM)

Professional affiliations: Japan Society of Applied Physics (JSAP). 2019 - 2025.

Toyota Scholarship Award in 2019, one of three recipients (Ph.D.).

Distinguished academic record 2015, GPA: 3.6 (M.Sc.).

Ranked among top 200 out of 15000 participants in national entrance exam for M.Sc. material science and engineering, 2012.

Social links

hanif.mohammadi@uni-kassel.de