Research

Optikal Radiation and Development of IR Photodedector

Our study of photonics comprises everything from the fundamental physical properties of photonic technologies to their electro-optical characterization as well as their applications (especially thermal cameras).
With the rapid development of photonics and photonics-enabled technologies, there is a growing demand for qualified experts to fill photonics-based positions. From an educational standpoint, this means that courses in photonic and related technologies can educate qualified graduates students for these positions. Introducing graduate students to the basics and applications of photodetectors can fullfil the requirements. Specifically, by means of teaching the fundamentals of IR radiation and thermal-imaging techniques and teaching how photodetectors and thermal imagers function, students can get familiarized with photodetector operations and sensor performance calculations.

Furthermore, industrial and various other applications in Surface science/interfacial electrochemistry systems. Therefore,  introduction the basics of surface processes of metal and semiconductor devices as well as in an electrolytes (i.e., describing surface diffusion/adsorption processes at solid electrode-electrolyte interfaces).
Object of our current research is in the field of IR imaging systems (detectors). More specifically, we are looking at detectors working in the mid-wavelength-infrared (MWIR) spectral range from 3 to 5 µm. Such devices are important in many different fields, includingastronomy, medicine, industrial processes and law enforcement. The material most often used in detectors for these applications has been bulk mercury cadmium telluride (MCT). IR detectors based on indium arsenide and gallium antimonide (InAs/GaSb) superlattices (SLs) have also shown promise as candidates for MWIR applications. The advantage of InAs/GaSb SLs over bulk MCT is their strongly suppressed Auger recombination rates, which significantly reduce noise current.

Superlattice Photodedector device (Packaged sample ready to measure)

The “true” Dedectivity D* is significantly different from the theoretical D* values
We are presently extending our work to include low cost IR manufacturing.
The process technologies for silicon-based devices (particularly photodetector systems) are driven by low cost and high performance. Silicon (Si) doped with supersaturated chalcogens by ion implantation and subsequent pulsed-laser melting exhibits a strong absorption to near- IR (2500 nm) radiation. Here, we propose a systematic investigation to exploit this characteristic to develop novel silicon-based IR photodetectors and photovoltaics.

Having experience with different optoelectronic devices, we are interested in innovative new ideas both in IR physics and its applications, including photodectors and lasers, Photonics-Enabled Fields.

Scanning electron microscope images of sulfur (S)/Silicon(Si) Surfaces morphology created by pulsed-laser melting methods

Energy dispersive X-ray spectroscopy (EDX)  image of S/Si sample

We also interested in Surface metrology (nanotechnology). Since, the improvement/developments, structure and quality assurance problems often occur concerning the materials, their properties and suitability and very often the surface/interface processes of materials.

Scanning tunneling microscope (STM) image of Chlore adsorbates on Copper Surface (imge size 36X30Å2)

Plasmonics:


      Plasmonics is one of the hottest topics, on which a vast amount of research is being conducted by physicists, chemists, biologists and engineers. Plasmons are collective oscillations of free electrons in both metals and semiconductors. Nanoparticles of sizes 20nm-150nm ………..

 

Superluminal light propagation?


         It is really interesting that we, the physicists, can entangle two light pulses separated by 100s of km from each other, but we are unable to identify the propagation velocity of a pulse even in an ordinary dye solution  ………..

 

Quantum Optics with Bose-Einstein condensates:


     BEC is not only a statistical phase transition, but also a quantum many body phase transition. The entanglement among all of the constituent atoms resists decoherence and randomized temperature fluctuations …………..

 

Quantum Precision Measurements:


     We detect the spatial position of a cantilever much more precisely by coupling it to a BEC. In atomic force microscopy (AFM), the position of the tip is measured by directly monitoring the displacement of the mechanical oscillator (cantilever) by the deflection of the laser beam. We monitor the motion of the cantilever indirectly by conducting measurements on the BEC .…………..

 

Photonic crystal from BEC vortices:


     A rotating BEC manifests the formation of vortices after a critical rotation frequency. Utilizing the index enhancement scheme, a triangular lattice of BEC vortices can generate both directional and complete photonic band gaps.

 


Hacettepe Üniversitesi Nükleer Bilimler Enstitüsü
06800 Beytepe / Ankara
Tel: (0312) 297 68 80