Enhancing short-wave infrared photosensing of germanium-based nanocrystals
Ana-Maria Lepadatu 1, Catalin Palade 1, Adrian Slav 1, Ionel Stavarache 1, Ioana Dascalescu 1, Ovidiu Cojocaru 1, Valentin-Adrian Maraloiu 1, Valentin S. Teodorescu 1,2, Toma Stoica 1, and Magdalena L. Ciurea 1,2 1 National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania; 2 Academy of Romanian Scientists, 54 Splaiul Independentei, 050094 Bucharest, Romania
The detection of SWIR light is a key technology for many burgeoning industries, covering a broad range of applications, e.g. night vision, biomedical imaging, pollution monitoring, industrial inspection (food quality), chemical sensing or solvent recognition. The market is dominated by III-V and II-VI compounds with complicated and costly heterogeneous integration, also with toxicity issues. A strategy to avoid these problems is to employ the more sustainable Ge-based nanostructures with great potential for developing cost-effective and CMOS-compatible SWIR applications. By developing films of group IV based nanocrystals (NCs) embedded in oxides, benefits from using both NCs and oxide matrix are exploited. The embedding matrix passivates the NC surface, while tailoring NCs size, composition (by alloying) and strain enables tuning and enhancement of optoelectronic properties. In my talk, I will review the VIS-NIR photosensing (photocurrent) in Ge NCs/quantum dots (QDs) embedded in oxides and I will discuss limitations, and I will show the enhancement of SWIR photosensing by alloying Ge with Si and by embedding matrix-induced passivation, stress field and nanocrystallization effects. Further strategy for boosting SWIR photosensitivity of Ge by alloying with Sn will be highlighted.