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Size and Shape Controlled Semiconductor Nanocrystals Synthesized by RF‐Sputtering Techniques for Electronic and Optoelectronic Applications
Author(s) -
Lehninger D.,
Beyer J.,
Schneider F.,
Pawlik A.S.,
Heitmann J.
Publication year - 2015
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.201510017
Subject(s) - materials science , nanocrystal , amorphous solid , annealing (glass) , photoluminescence , sputter deposition , optoelectronics , sputtering , crystallization , nanotechnology , thin film , chemical engineering , composite material , crystallography , chemistry , engineering
Group IV (Ge and Si) nanocrystals embedded in a dielectric matrix were prepared via rf magnetron sputtering by the deposition of superlattices of stoichiometric and substoichiometric oxide layers and subsequent annealing. By this way Ge nanocrystals in a (Ta)ZrO x and Si nanocrystals in an SiO 2 matrix were prepared in a size and shape controlled manner. In case of the Ge‐ZrO 2 system, elongated Ge nanocrystals in a crystallized ZrO 2 matrix were formed for annealing temperatures above 660 °C. Starting from a Si 3 N 4 interface of the Si wafer, a preferential orientation between the Ge and ZrO 2 lattice can be stated. Doping the ZrO 2 matrix additionally with Ta increases the crystallization temperature of the ZrO 2 matrix and leads to the formation of Ge nanocrystals embedded in an amorphous TaZrO x matrix. The Ge nanocrystals were investigated by photoluminescence measurements and implemented into metal‐insulator‐semiconductor capacitor to investigate their potential for charge trapping devices. The prepared nano floating gate devices show good charging characteristics with a maximum memory window of 5 V and a slope of the writing voltage vs. memory window characteristics of 0.8‐1. All luminescence centers seen in the Ge‐(Ta)ZrO x system can be attributed to defects either from the Ge nanocrystal surface, the (Ta)ZrO x matrix or the Si substrate itself. Si nanocrystals were fabricated in the same way in an amorphous SiO 2 film after annealing above 900 °C. The formed Si nanocrystals act as superior sensitizer for Er 3+ ions which were ion implanted into the films followed by an additional subsequent anneal, varied between 700 and 1000 °C. The Si nanocrystal ‐ Er 3+ system was successfully implemented into a slot waveguide structure showing a strong polarization dependent field enhancement in both emission and excitation geometry. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)