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SUMMARY:Graphene/hBN - based varactor for novel sub-THz phase shifter.
DTSTART;VALUE=DATE-TIME:20220706T153500Z
DTEND;VALUE=DATE-TIME:20220706T155000Z
DTSTAMP;VALUE=DATE-TIME:20260314T132036Z
UID:indico-contribution-807@events.ncbj.gov.pl
DESCRIPTION:Speakers: Piotr Dróżdż (CENTERA Laboratories\, Institute of
  High Pressure Physics\, PAS)\nThe mm-wave and terahertz (THz) frequency r
 anges are gaining much attention recently due to their high applicability\
 , which creates a need for the development of the devices operating in abo
 vementioned frequency ranges. One among the most important elements of suc
 h THz devices (e. g. Phase shifters) are varactors (variable capacitors)\,
  that allow tuning of the system via electrically-induced capacitance shif
 t. In [1]\, the carbon nanotubes (CNTs) MicroElectroMechanical System (MEM
 S) varactor is described.  \n\nThe device consists of series of etched tre
 nches with metallized bottoms structuring the bottom electrode. On top of 
 the trenches\, the layer of CNTs is placed\, serving as a top electrode. W
 hen voltage is applied between the top/bottom electrodes\, the electricall
 y-formed force causes the nanotube layer to bend towards the bottom electr
 ode resulting in distance reduction that in final increases the capacitanc
 e. \n\nHowever\, CNTs are known from changing the capacity by themselves w
 hen exposed to various environmental conditions like temperature variation
 \, humidity or illumination.  \n\nHere\, we present the new type of the va
 ractor fabricated upon silicon/SixNy platform with use of carbon-based met
 amaterials. The design of the structure is inspired by the one reported in
  [1]. However\, in our approach\, graphene (GR) is used as a top electrode
 \, since it seems to be more stable and immune against external environmen
 t conditions. Futher stability improvement is achieved by covering GR with
  PMMA protective layer. To avoid shorting between GR and bottom electrode 
 an hBN insulating layer was placed under GR.  \n\nWe present the character
 isation measurements of the metamaterial layers used in our device. Finall
 y\, the electrical characterisation of working device is presented includi
 ng I - V and C - V characteristics\, which appear to be linear. The tunabi
 lity of our devices seems to be of the order of few hundred pF/V. \n\n[1] 
 A. A. Generalov et al.\, Nanotechnology 26\, 045201 (2015).\n\nhttps://eve
 nts.ncbj.gov.pl/event/75/contributions/807/
LOCATION:Novotel Warszawa Centrum Róża
URL:https://events.ncbj.gov.pl/event/75/contributions/807/
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