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(Color online) TEM images of (a) thin and (b) thick Ni-InGaAs formed on In0.53Ga0.47As substrate. (c) The high resolution image shows the periodic arrangement of atoms in Ni-InGaAs layer, demonstrating good crystalline quality.
(Color online) He I (hv = 21.2 eV) UPS spectra of thick Ni-InGaAs formed on In0.53Ga0.47As. A −5 V bias was applied to the Ni-InGaAs layer. Fermi edge position was determined as the center of the slope as indicated by the vertical line. Secondary electron cut-off position was determined from the intercept of the slope with the background level.
(Color online) Normalized XPS core-level spectra of (a) As 3d for bulk Ni-InGaAs (bottom) and In0.53Ga0.47As (top) samples. Comparison of (b) As 3d, (c) In 3d5/2, and (d) Ga 2p3/2 from Ni-InGaAs/In0.53Ga0.47As interface sample (bottom) and from bulk In0.53Ga0.47As (top). The red (dotted) and blue (solid) fitted curves correspond to signal coming from Ni-InGaAs and In0.53Ga0.47As, respectively. The In 3d5/2, Ga 2p3/2, and As 3d peaks at the interface reside 0.75 eV higher than that of In0.53Ga0.47As substrate determined by the difference between the blue fitted curves.
(Color online) (a) Schematic energy band diagram showing band alignment of Ni-InGaAs in contact with In0.53Ga0.47As substrate consistent with XPS results. Interface dipole or Fermi level pinning could lead to a high electric field at the Ni-InGaAs/InGaAs interface represented by dotted band profile. (b) I-V characteristic measured between Ni-InGaAs pad and Au back-side contact to InP of diode structure (inset). The Ni-InGaAs/p-In0.53Ga0.47As junction shows rectifying behavior.
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