Electronic structure of InN observed by magnetoresistance

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Electronic structure of InNobserved by
magnetoresistance

T. Inushima Tokai University,
Japan M. Higashiwaki and T. Matsui
Nat. Inst. Info. Comm. Tech, Japan T. Takenobu
and M. Motokawa IMR, Tohoku
University, Japan
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Background

• Reported results
• Band-gap energy of InN is 0.6 eV
• InN is still degenerated semiconductor at the
  carrier density of 3x1017cm-3
• Effective mass of InN is 0.040.085m0
• Surface accumulation layer exists
• Direct observation of the electronic structure of
  InN by magnetoresistance
• as a function of carrier density

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Si-doped InN
Higashiwaki et al., PSS 240, 420 (03)
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B
Experimental conditions

• 4-probe method at
• 0.54.2 K
• Bc-axis
• Current10-10 11-20
• Field 013 T
• InN Si-doped d250 nm (n1.815?1018cm-3,
  me10001570 cm2V-1s-1)

I10-10
I11-20
090
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Temperature dependence of the resistivity
252 non-doped inN (1.8 1018cm-3) 238 Si-doped
InN (3.0) 248 Si-doped InN (15)
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Temperature dependence of the resistivity change
of Si-doped InN
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Carrier density dependence of the conductivity
at 0.5 K

• Zero temperature conductivity depends on the
  current direction
• InN investigated is in the metallic side of Mott
  transition

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Magnetoresistance at BI(angle dependence )
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SdH at TMR and LMR
I10-10
I11-20
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Shubnikov-de Haas oscillation

• mechanism of SdH

Cross section of Extremal orbit of Fermi sphere
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Conditions for SdH observation

• mobilitygt1000 cm2/Vs(at 10T)
• grain sizegt cyclotron radius (at 10 T)

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SdH signal expression
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Analysis of SdH oscillations at B I
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Carrier density of N and N
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Carrier density dependence of N N
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Intrinsic electron accumulation at InN surface
C. H. Swartz et al., J. Crystal Growth 269, 29
(04)
I. Mahboob et al., PRL 92, 036804 (04)
wtlt1
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Angle dependence of SdH at 2D electron gas
wtgt1, BZBcosq
J. R. Lowney et al., J. Elec. Materials 22, 985
(1993), MCT surface
L. L. Chang et al., PRL 38, 1489 (1977) GaAlAS
super lattice
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Negative magnetoresistance of semiconductors
Negative magnetoresistance observed at
Si-inversion layer and InAs at accumulation layer
(B surface) was normal effect due to the
Lorentz force explained by Uemura and Matsumoto.
S. Tansal et al., P. R. 178, 1326 (1969)
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Anomalous magnetoresistance of p-doped Si at
Bsurface
C. Yamaguchi et al., J. Phys. Soc. Jpn. 22, 859
(1967)
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Anderson localization by S. Kawaji and Y.
Kawaguchi
electron localization in the a-b plane
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Substantial carrier density dependence of the
corrected zero temperature conductivity
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Band structure of InN at the fundamental
absorption edge
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Summary

• Electronic structure of InN was measured by
  magnetoresistance
• Fermi surface of InN is anisotropic
• There is a spherical Fermi surface and its radius
  increases according to the increase of carrier
  density
• There is a structure in the a-b plane with the
  constant carrier density of 4.5?1012cm-2
• Critical density of the Mott transition should be
  2?1017cm-3
• Electronic structure of the fundamental
  absorption edge of InN grown on sapphire (0001)
  was presented

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I11-20 and Bc-axis
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Longitudinal magnetoresistance
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(No Transcript)
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Magnetoresistance at BI(angle dependence )
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Electron distribution of MCT accumulation layer