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SUMMARY:Investigation of doping and dopant dependence of n-type 4H-SiC wit
 h low-energy muon spin spectroscopy
DTSTART;VALUE=DATE-TIME:20220830T164000Z
DTEND;VALUE=DATE-TIME:20220830T170000Z
DTSTAMP;VALUE=DATE-TIME:20220826T120700Z
UID:indico-contribution-3729@indico.stfc.ac.uk
DESCRIPTION:Speakers: Maria Mendes Martins (Laboratory for Muon Spin Spect
 roscopy\, Paul Scherrer Institute)\nSilicon carbide (4H-SiC) is a wide-ban
 dgap semiconductor with applications in high power devices. Epitaxial grow
 th of SiC is crucial to produce structures with controlled thickness and d
 oping concentration. Ion implantation with nitrogen (N) and phosphorus (P)
 \, on the other hand\, is used to create spatially defined n-type regions 
 in SiC. Implantation is usually followed by a post-implantation annealing 
 step\, to ensure lattice recovery and electrical activation of the donors.
  However\, mitigating implantation-induced defects remains a challenge.\n\
 nThe narrow defective regions$\\\;$(200-300$\\\;$nm) are not accessible by
  conventional techniques\, but can be studied with low-energy muon-spin sp
 ectroscopy (LE-$\\mu$SR). The LE-$\\mu$SR experiments were performed at th
 e low-energy muon facility at the S$\\mu$S (PSI\, Switzerland). The 4H-SiC
  samples were either doped with N during epitaxial growth$\\\;$(N$_D=4\\ti
 mes$10$^{15}\\\;$and$\\\;1\\times$10$^{17}\\\;$cm$^{-3}$)$\\\;$or using io
 n-implantation of N and P$\\\;$(N$_D=1\\times$10$^{17}\\\;$and$\\\;1\\time
 s$10$^{18}\\\;$cm$^{-3}$). The goal was to compare the different doping pr
 ocesses and to establish a $\\mu$SR baseline for different doping concentr
 ations in n-type SiC.\n\nWe find that an effective electron concentration 
 (*n*)$\\\;$of$\\\;4\\times$10$^{15}\\\;$cm$^{-3}$ in SiC is below the sens
 itivity limit of LE-$\\mu$SR. For N$_D>$1$\\times$10$^{17}\\\;$cm$^{-3}$\,
  there is an intermediate space charge region where muonium (Mu$^0$) forma
 tion dominates and the diamagnetic fraction (F$_D$) decreases. In the deep
 er probed region\, F$_D$ increases with doping concentration due to Mu$^-$
  formation. F$_D$ also increases between $10\\\;$and$\\\;0.5\\\;$mT indica
 ting delayed Mu$^-$ formation\, having a Mu$^0$ precursor state. For the i
 mplanted samples\,$\\\;10\\\;$K measurements indicate higher defect densit
 y for$\\\;1\\times$10$^{18}\\\;$cm$^{-3}$\, which can be related to the hi
 gher implantation dose. \nFurthermore\, Monte Carlo simulations were used 
 to generate muon decay histograms for different electron capture rates\, t
 o determine F$_D$ and the phase of the diamagnetic signal as function of *
 n*\, which agree with the experimental results. This means\, that *n* can 
 be determined for a SiC sample with unknown carrier concentration by compa
 ring  the experimental results of F$_D$ and the phase with the results of 
 the simulation.\n\nhttps://indico.stfc.ac.uk/event/53/contributions/3729/
LOCATION:Science and Technology Campus\, University of Parma
URL:https://indico.stfc.ac.uk/event/53/contributions/3729/
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