2. Articole

Permanent URI for this collectionhttps://msuir.usm.md/handle/123456789/47

Browse

Start date: 2020Subject: search.filters.subject.terahertz (THz) radiation

Search Results

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    RECENT PROGRESS IN GaN-BASED DEVICES FOR TERAHERTZ TECHNOLOGY
    (Springer Nature, 2020) Sirkeli, Vadim; Tiginyanu, Ion; Hartnagel, Hans
    This paper reviews the crystal growth, basic properties, and principle of operation of III-nitride based terahertz devices. We provide a brief history and current status of crystal growth of polar and non-polar GaN-based heterostructures and its properties. The role of spontaneous and piezoelectric polarization in polar III-nitride structures and its impact on performance of terahertz devices is discussed in detail. We show that GaN-based semiconductor compounds are promising materials for fabrication terahertz sources operating up to room temperature due to their unique properties such as large bandgap and conduction band offset (CBO) energy, high LO-phonon energy, and high resistant to the high breakdown electric field. Moreover, it was established that the GaN-based terahertz sources can cover the spectral region of 5–12 THz, which is very important for THz imaging and detection of explosive materials, and which could be not covered by conventional GaAs-based terahertz devices. In terms of the reported significant progress in growth of non-polar m-plane GaN-based heterostructures and devices with low density defects, it is open a wide perspective towards design and fabrication of non-polar m-plane GaN-based high power terahertz sources with capabilities of operation at room temperature.
  • Thumbnail Image
    Item
    ZnO-BASED QUANTUM STRUCTURES FOR TERAHERTZ SOURCES
    (Springer Nature, 2020) Sirkeli, Vadim; Hartnagel, Hans; Yilmazoglu, O.; Preu, S.
    In this paper we report on the numerical study of the terahertz devices based on metal oxide semiconductors and its application in biology and medicine. We also report on the recent progress of the theoretical and experimental studies of ZnO-based THz quantum cascade lasers (QCLs) and resonant tunneling diodes (RTDs). We show that ZnO-based semiconductor compounds are promising materials for fabrication terahertz sources operating up to room temperature due to their unique properties such as large bandgap and conduction band offset (CBO) energy, high LO-phonon energy, and high resistant to the high breakdown electric field. Moreover, it was established that the ZnO-based terahertz sources can cover the spectral region of 5–12 THz, which is very important for THz imaging and detection of explosive materials, and which could be not covered by conventional GaAs-based terahertz devices. In terms of the reported significant progress in growth of non-polar m-plane ZnO-based heterostructures and devices with low density defects, it is open a wide perspective towards design and fabrication of non-polar m-plane ZnO-based high power terahertz sources with capabilities of operation at room
  • Thumbnail Image
    Item
    RECENT ADVANCES IN TERAHERTZ TECHNOLOGY FOR SECURITY AND BIOMEDICAL APPLICATIONS
    (Universitatea de Stat din Tiraspol, 2021) Sirkeli, Vadim
    Terahertz waves have low photon energies (~ 4.1 meV for 1 THz), which is about 1 million times weaker than the energy of X-ray photons. They do not cause any harmful ionization in biological tissues. The terahertz radiation is strongly attenuated by water and is very sensitive to water content. This paper provides current status and recent advances in terahertz technology for security and medical applications. In particular, we report on our designs of THz quantum cascade lasers to identify cancerous tissues and other medical issues.
  • Thumbnail Image
    Item
    THZ SPECTROSCOPY BY NARROW SPECTRAL EMISSION OF QUANTUM CASCADE LASERS FOR MEDICAL APPLICATIONS
    (Institute of Electrical and Electronics Engineers, 2021) Hartnagel, Hans; Sirkeli, Vadim; Acedo, Pablo
    THz waves have low photon energies (~ 4.1 meV for 1 THz), which is about 1 million times weaker than the energy of X-ray photons. They do not cause any harmful ionization in biological tissues. The terahertz radiation is strongly attenuated by water and is very sensitive to water content. The interest in terahertz imaging and spectroscopy of biologically related applications is increasing. This paper provides current status and recent advances in terahertz spectroscopy techniques in biological and medical applications. In particular, we report on our designs of THz Quantum-Cascade sources to identify cancerous tissues and other medical issues.
  • Thumbnail Image
    Item
    ZnO FOR INFRARED AND TERAHERTZ APPLICATIONS
    (Elsevier, 2021) Sirkeli, Vadim; Hartnagel, Hans
    This chapter reviews the recent progress of the theoretical and experimental studies of ZnO-based structures such as quantum cascade lasers, resonant-tunneling diodes, and quantum well detectors and their applications for infrared and terahertz spectral range. The role of spontaneous and piezoelectric polarization in polar ZnO-based structures and their impact on intersubband transitions and the performance of terahertz devices are discussed in detail. It is shown that ZnO-based compounds are promising materials for the fabrication of terahertz sources operating up to room temperature due to their unique properties such as their large bandgap, conduction band offset energy, and high longitudinal-optical phonon energy. Moreover, ZnO-based terahertz sources can cover the spectral region of 0.1–12 THz, which is very important for THz imaging and detection of explosive materials and medical spectroscopy applications, which could be not covered by conventional GaAs-based terahertz devices. In terms of the reported significant progress in the growth of nonpolar m-plane ZnO-based heterostructures and devices with low defect density, a wide perspective for the design and fabrication of high-power terahertz sources at room-temperature operation is now opened up.