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Title: Thermal effects on the Raman phonon of few-layer phosphorene

Two-dimensional phosphorene is a promising channel material for next generation transistor applications due to its superior carrier transport property. Here, we report the influence of thermal effects on the Raman phonon of few-layer phosphorene formed on hafnium-dioxide (HfO{sub 2}) high-k dielectric. When annealed at elevated temperatures (up to 200 °C), the phosphorene film was found to exhibit a blue shift in both the out-of-plane (A{sup 1}{sub g}) and in-plane (B{sub 2g} and A{sup 2}{sub g}) phonon modes as a result of compressive strain effect. This is attributed to the out-diffusion of hafnium (Hf) atoms from the underlying HfO{sub 2} dielectric, which compresses the phosphorene in both the zigzag and armchair directions. With a further increase in thermal energy beyond 250 °C, strain relaxation within phosphorene eventually took place. When this happens, the phosphorene was unable to retain its intrinsic crystallinity prior to annealing, as evident from the broadening of full-width at half maximum of the Raman phonon. These results provide an important insight into the impact of thermal effects on the structural integrity of phosphorene when integrated with high-k gate dielectric.
Authors:
;  [1] ;  [2]
  1. Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583 (Singapore)
  2. (Singapore)
Publication Date:
OSTI Identifier:
22499225
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL Materials; Journal Volume: 3; Journal Issue: 12; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANNEALING; DIELECTRIC MATERIALS; DIFFUSION; FILMS; HAFNIUM; HAFNIUM OXIDES; HYDROFLUORIC ACID; LAYERS; PHONONS; TEMPERATURE DEPENDENCE; TRANSISTORS