Epitaxial GeSn Obtained by High Power Impulse Magnetron Sputtering and the Heterojunction with Embedded GeSn Nanocrystals for Shortwave Infrared Detection

Ioana Dascalescu; Nicolae C Zoita; Adrian Slav; Elena Matei; Sorina Iftimie; Florin Comanescu; Ana-Maria Lepadatu; Catalin Palade; Sorina Lazanu; Dan Buca; Valentin S Teodorescu; Magdalena L Ciurea; Mariana Braic; Toma Stoica

doi:10.1021/acsami.0c06212

Epitaxial GeSn Obtained by High Power Impulse Magnetron Sputtering and the Heterojunction with Embedded GeSn Nanocrystals for Shortwave Infrared Detection

ACS Appl Mater Interfaces. 2020 Jul 29;12(30):33879-33886. doi: 10.1021/acsami.0c06212. Epub 2020 Jul 15.

Authors

Ioana Dascalescu^{1

2}, Nicolae C Zoita³, Adrian Slav¹, Elena Matei¹, Sorina Iftimie², Florin Comanescu⁴, Ana-Maria Lepadatu¹, Catalin Palade¹, Sorina Lazanu¹, Dan Buca⁵, Valentin S Teodorescu^{1

6}, Magdalena L Ciurea^{1

6}, Mariana Braic³, Toma Stoica¹

Affiliations

¹ National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania.
² Faculty of Physics, University of Bucharest, 405 Atomistilor Street, 077125 Magurele, Romania.
³ National Institute for Research and Development in Optoelectronics, 409 Atomistilor Street, 077125 Magurele, Romania.
⁴ National Institute for Research and Development in Microtechnologies, 077190 Voluntari, Romania.
⁵ Peter Grünberg Institut 9 (PGI 9) and JARA Fundamentals of Future Information Technologies, Forschungszentrum Jülich, 52425 Jülich, Germany.
⁶ Academy of Romanian Scientists, Bucharest, 050094 Bucharest, Romania.

PMID: 32633935
DOI: 10.1021/acsami.0c06212

Abstract

GeSn alloys have the potential of extending the Si photonics functionality in shortwave infrared (SWIR) light emission and detection. Epitaxial GeSn layers were deposited on a relaxed Ge buffer on Si(100) wafer by using high power impulse magnetron sputtering (HiPI-MS). Detailed X-ray reciprocal space mapping and HRTEM investigations indicate higher crystalline quality of GeSn epitaxial layers deposited by Ge HiPI-MS compared to commonly used radio frequency magnetron sputtering (RF-MS). To obtain a rectifying heterostructure for SWIR light detection, a layer of GeSn nanocrystals (NCs) embedded in oxide was deposited on the epitaxial GeSn one. Embedded GeSn NCs are obtained by cosputtering deposition of (Ge_1-xSn_x)_1-y(SiO₂)_y layers and subsequent rapid thermal annealing at a low temperature of 400 °C. Intrinsic GeSn structural defects give p-type behavior, while the presence of oxygen leads to the n-character of the embedded GeSn NCs. Such an embedded NCs/epitaxial GeSn p-n heterostructure shows superior photoelectrical response up to 3 orders of magnitude increase in the 1.2-2.5 μm range, as compared to performances of diode based only on embedded NCs.

Keywords: GeSn nanocrystals; GeSn sputtering epitaxy; SWIR photosensitivity; heterojunction diode; high power impulse magnetron sputtering HiPIMS; in situ and ex situ GeSn annealing; strain relaxation.