Laboratory for Electrical Properties of Semiconductors
Head
Ewa Popko
office: 231 A, A-1
phone: +48 71 320 26 42
Eunika Zielony
phone: +48 71 320 26 42
Krzysztof Gałkowski
office: 405, A-1
phone: +48 71 320 37 40
Katarzyna Gwóźdź
office: 231A, A-1
phone: +48 71 320 26 42
Zbigniew Gumienny
office: 231B, A-1
phone: +48 71 320 23 90
PhD Students
Adrian Kaim
office: 434, A-1
Igor Perlikowski
office: 434, A-1
Radosław Szymon
office: 434, A-1
Research
From fundamental research of nanostructure to development of modern technology. Our research team specializes in investigations of semiconductor materials and nanostructures by means of various electrical and photoelectrical experimental techniques. Historically, the name of our group – Laboratory for Electrical Properties of Semiconductors (LEPS) – has been associated with the primary branch of scientific research we have conducted in the past and continue to this day. The research is focused on studying defects, current transport mechanisms, and the electrical properties of semiconductor junctions, such as Schottky diodes, p-i-n diodes, and p-n junctions, using electrical measurement techniques. The techniques include current-voltage (I-V) and capacitance-voltage (C-V) measurements, as well as admittance spectroscopy and deep-level transient spectroscopy (DLTS), along with its variants, such as LDLTS, ODLTS, PICTS and others.
Over time, our research scope has significantly expanded. Nowadays, LEPS also focuses on studying structural properties of various materials using atomic force microscopy (AFM) and Raman spectroscopy. We utilize Raman scattering technique to analyze strain and the crystal lattice dynamics in various solid materials. Additionally, our research includes investigating the optical properties of semiconductor structures. In optical measurements, we employ photoluminescence (PL) and perform spectral measurements of transmission, reflection, photocurrent, and quantum efficiency. All of these techniques are available in one of our core labs – National Laboratory for Quantum Technologies – where we utilize state-of-the-art equipment and the extensive expertise of our team to carry out fundamental research on physics, technology, and material engineering.
LEPS is also equipped with a solar simulator, enabling I-V curves measurements over a broad temperature range. These studies are conducted on semiconductor structures with potential applications as solar cells. Furthermore, we focus on the characterization of photodetector structures using a self-made system for measuring various photodetector parameters, such as responsivity, detectivity, and sensitivity. This system incorporates a current amplifier, as well as LED and laser light sources operating across a wide range of wavelengths, allowing also for changes in conditions, such as temperature or strain.
Currently, our research is divided into three main scientific areas:
(1) Optoelectronics: including investigations of pyrophototronic detectors that do not require external power supply based on the pyroelectric, photovoltaic, ferroelectric and/or plasmonic phenomena; basic research on structures with nanowires and quantum wells based on Zn(Cd,Mg)O and AlGaN/GaN compounds for applications in light emitters (e.g. laser diodes); basic research on structures with GaN-based nanowires, including metallic layers, which will ensure the so-called recycling of photons extending their absorption path in the active layer of light emitters; fundamental studies of light soaking/phase segregation process and defect passivation in metal-halide perovskites.
(2) Electronics: characterizing defects in semiconductors used in electronics, i.e. silicon, gallium arsenide, gallium nitride, zinc oxide, etc.
(3) Photovoltaics: characterizing new materials for inorganic and pervoskite photovoltaic cells.