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SUMMARY:Novel high quality GeSn and GePb alloys for mid-infrared photodete
 ctors
DTSTART:20260605T080000Z
DTEND:20260605T084500Z
DTSTAMP:20260624T041800Z
UID:indico-event-1857@indico.dfa.unipd.it
DESCRIPTION:Speakers: Jim Williams (Research School of Physics\, Australia
 n National University\, ACT 2601\, Australia)\n\nJim Williams and Michael 
 Eksteen\nResearch School of Physics\, Australian National University\, ACT
  2601\, Australia\nGeSn and more recently GePb alloys have attracted atten
 tion as promising candidates for fabricating mid-infrared photodetectors o
 perating up to 10 µm. However\, the growth of both alloys on Ge or Si sub
 strates is challenging since the equilibrium Sn solid solubility in Ge is 
 less than 1% and the Pb solubility is in the parts per million range. Also
 \, the lattice mismatch between Ge and GeSn or GePb causes threading dislo
 cations during film relaxation to equilibrium lattice spacings. Both aspec
 ts have been found to severely degrade the photodetector performance.\nThi
 s presentation covers the progress that we have made on overcoming the lim
 itations of the current GeSn and GePb materials. Specifically\, a main obj
 ective of our approach has been to pursue avenues for defect reduction in 
 both remote plasma enhanced CVD (RPECVD)-grown GeSn films and also GeSn fi
 lms produced by a combination of Sn-ion implanted Ge and pulsed laser melt
 ing (PLM)\, to provide suitable material for high performance photodetecto
 rs. A second objective has been to develop a satisfactory n-type doping pr
 ocedure for GeSn films based on ion implantation and PLM. A further object
 ive has involved characterising strained and relaxed Ge-GeSn superlattices
  grown by RPECVD\, and a final objective has been to investigate the possi
 ble production of GePb films by ion implantation and PLM. Apart from a bri
 ef review of each of these areas\, specific focus will be given to the fol
 lowing two areas.\nParticular emphasis will be given to the following area
 s. i) Strained and strain-relaxed Ge-GeSn superlattices\, where we have ch
 aracterised superlattices of various compositions and thicknesses by a sui
 te of analytical methods. Using strain engineering approaches\, our result
 s show that defect-free\, fully-strained superlattices with more than 10 G
 e-GeSn pairs can be grown for high Sn concentrations. ii) We have achieved
  around 0.5 atomic % of Pb in Ge which is 5 orders of magnitude above the 
 equilibrium solubility limit. Pb segregation to the surface and Pb-rich fi
 lamentary behaviour during rapid solidification of molten Ge limit the Pb 
 content in Ge. iii) Towards efficient n-type doping of Ge and GeSn\, where
  we have found that compensating p-type centres that are present in both G
 e and GeSn severely limit n-type doping.  Following implantation we have 
 studied several annealing methods from RTA to PLM and used Rutherford back
 scattering and channelling and TEM\, along with Hall effect and magnetores
 istance\, to characterise the samples.\nSeminar organized by the Semicondu
 ctor Physics Group & Advanced Crystals\n\nhttps://indico.dfa.unipd.it/even
 t/1857/
LOCATION:1/3-1 - Sala R (Dipartimento di Fisica e Astronomia - Edificio Ma
 rzolo)
URL:https://indico.dfa.unipd.it/event/1857/
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