| Autor: |
Palade C; National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania., Lepadatu AM; National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania., Slav A; National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania., Teodorescu VS; National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania.; Academy of Romanian Scientists, 54 Splaiul Independentei, 050094 Bucharest, Romania., Stoica T; National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania., Ciurea ML; National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania.; Academy of Romanian Scientists, 54 Splaiul Independentei, 050094 Bucharest, Romania., Ursutiu D; Academy of Romanian Scientists, 54 Splaiul Independentei, 050094 Bucharest, Romania.; Department of Electronics and Computer Science, Transylvania University of Brasov, 29 Eroilor, 500036 Brasov, Romania., Samoila C; Department of Materials Science, Transylvania University of Brasov, 29 Eroilor, 500036 Brasov, Romania.; Romanian Technical Science Academy, 26 Dacia, 010413 Bucharest, Romania. |
| Abstrakt: |
Group IV nanocrystals (NCs), in particular from the Si-Ge system, are of high interest for Si photonics applications. Ge-rich SiGe NCs embedded in nanocrystallized HfO 2 were obtained by magnetron sputtering deposition followed by rapid thermal annealing at 600 °C for nanostructuring. The complex characterization of morphology and crystalline structure by X-ray diffraction, μ-Raman spectroscopy, and cross-section transmission electron microscopy evidenced the formation of Ge-rich SiGe NCs (3-7 nm diameter) in a matrix of nanocrystallized HfO 2 . For avoiding the fast diffusion of Ge, the layer containing SiGe NCs was cladded by very thin top and bottom pure HfO 2 layers. Nanocrystallized HfO 2 with tetragonal/orthorhombic structure was revealed beside the monoclinic phase in both buffer HfO 2 and SiGe NCs-HfO 2 layers. In the top part, the film is mainly crystallized in the monoclinic phase. High efficiency of the photocurrent was obtained in a broad spectral range of curves of 600-2000 nm at low temperatures. The high-quality SiGe NC/HfO 2 matrix interface together with the strain induced in SiGe NCs by nanocrystallization of both HfO 2 matrix and SiGe nanoparticles explain the unexpectedly extended photoelectric sensitivity in short-wave infrared up to about 2000 nm that is more than the sensitivity limit for Ge, in spite of the increase of bandgap by well-known quantum confinement effect in SiGe NCs. |
