1194 Russian Physics Journal, Vol. 61, No. 7, November, 2018 (Russian Original No. 7, July, 2018) PARAMETERS OF PHOTO-SENSITIVE STRUCTURES BASED ON Ge/Si NANOGETEROSTRUCTURES R. M. H. Douhan, A. P. Kokhanenko, and K. A. Lozovoy UDC 621.315.592 Infrared photodetectors with germanium quantum dots on silicon are considered. Some characteristics of such detectors are calculated, namely: dark current and detectivity in the modes of limitation by background and generation-recombination noises. A comparison is also made of the performance of quantum-dot infrared detectors with the performance of HgCdTe detectors. Keywords: quantum dots, silicon, germanium, nanostructures, molecular beam epitaxy, photodetector, dark current, detectivity. INTRODUCTION With the introduction of molecular beam epitaxy (MBE) in the technology of creating low-dimensional structures in 1970 [1] interest in semiconductor nanoscale solid-state structures has continuously increased over the years, leading to new technological breakthroughs, the discovery of new physical concepts, and promising applications. A new class of materials has also been developed, including materials with quantum dots possessing unique optoelectronic properties [2, 3]. Quantum dots exhibit unique properties due to the quantum limitation of carrier motion in all three spatial directions. These unique properties revealed a large potential of quantum dots for optoelectronic applications. They are promising nanomaterials for next-generation optoelectronic devices, such as lasers, photodetectors, amplifiers, and solar cells. They are the subject of research of numerous scientific groups around the world [4, 5]. In this paper, infrared photodetectors with germanium quantum dots on silicon are considered. The limiting characteristics of such photodetectors are calculated: dark current and detectivity in the modes of limitation by thermal noises, generation-recombination noises, and background radiation. The main parameters of quantum-dot infrared photodetectors made of a material with germanium quantum dots in silicon are also calculated. The results of comparing these photodetectors with other types of photodetectors are presented, and the differences between them are revealed. It is expected that photodetectors with quantum dots will be able to provide better performance, namely a higher operating temperature (due to the long carrier lifetime), a low dark current, and a high photoelectric gain. MODEL Among the performance characteristics of the photodetector, special attention should be paid to such parameters as dark current and detectivity. The detectivity of the photodetector D* reflects the signal-to-noise ratio, and the following formula is used for its calculation [6]: National Research Tomsk State University, Tomsk, Russia, e-mail: rahaf.douhan@gmail.com; kokh@mail.tsu.ru; lka@sibmail.com. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 8– 14, July, 2018. Original article submitted May 03, 2018. 1064-8887/18/6107-1194 2018 Springer Science+Business Media, LLC DOI 10.1007/s11182-018-1517-0