Photodetectors with GeSn nanocrystals in Si3N4 matrix highly photosensitive from 0.5 µm to 2.4 µm (GeSnPhotoSiNdet)
Project Director: Dr. Ionel STAVARACHE
Dr. Ionel Stavarache
Dr. Ana-Maria Lepadatu
Dr. Catalin Palade
Dr. Ioana-Maria Avram Dascalescu
Dr. Adrian Slav
Drd. Mihalcea Catalina-Gabriela
Dr. Catalin Negrila
Drd. Ovidiu Cojocaru
In the Stage I/2022, photodetector structures based on GeSnSi3N4 films in which the Sn concentration in the film was varied between ~4%vol. and ~ 18 %vol. were made. The films were deposited by magnetron sputtering on Si and quartz substrate maintained at room temperature during deposition.
The formation of GeSn nanocrystals/dots in GeSnSi3N4 films was achieved by thermal annealing RTA, after optimizing the necessary parameters, namely temperatures in the range of 325 - 700 °C.
The morphology and structure of the investigated films are strongly dependent on the Sn concentration in the GeSnSi3N4 films. In the amorphous films with increased Sn concentration, the structure is more dilated in the sense that the distance between the atoms in the first coordination sphere and the second coordination sphere is increased. This phenomenon also occurs in crystallized GeSn, i.e. the lattice constant increases with the increase in Sn concentration.
Optical investigations highlight the influence of the Sn concentration in the films on the absorption threshold. In the films where the Sn concentration is approximately 18 %vol, the absorption threshold has a value of 0.5 eV compared to the value of 0.7 eV corresponding to a Sn concentration of ~4 %vol.
The I – V characteristics obtained on GeSnSi3N4 / Si films show that the photocurrent is 4 orders of magnitude higher than the dark current and is strongly dependent on the measurement temperature. In addition, the spectral dependence of the photocurrent on these films presents a wide sensitivity band, in the range 520 - 1750 nm. The obtained results from the optical investigations are in agreement with the spectral ones and demonstrate that these films have adequate photoconductive properties for the manufacture of photodetectors.
In conclusion, the objectives and activities proposed for Stage I/2022 were fully achieved.
Lucrare indexata ISI:
“Extended near infrared photo-response influenced by host matrix change in Ge nanoparticle-based films”, I. Stavarache, C. Palade, A. Slav, P. Prepelita, V. S. Teodorescu, M. L. Ciurea, IEEE conference, 45th Edition of International Semiconductor Conference (CAS), pp. 231-234, 2022 October 12-14, Sinaia, Romania; IEEE Catalog Number: CFP22CAS-USB;
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