Au/N‐type Si Schottky‐barrier contact and oxidation kinetics in Au‐contaminated and thermally oxidized N‐type Si (001) surfaces

Abstract

Anomalous Au locations in SiO 2 /Si system of Au-contaminated and thermally oxidized n-type Si(001) have been investigated using XPS and alternating current surface photovoltage (AC SPV) techniques. On the basis of XPS analyses, in Au-contaminated (2 × 10 15 atoms/cm 2 ) and thermally oxidized Si surfaces between 823 and 973 K, the Au existed both on the top of the SiO 2 and the SiO 2 /Si interface as a cluster that did not make bonds with other elements such as O and H. The resulting Au/n-type Si Schottky barrier causes an occurrence of frequency-dependent AC SPV, demonstrating that the Si surface was depleted and/or weakly inverted. This result indicates that the Au/n-type Si Schottky barrier (calculated to be 0.70 eV) survived at the SiO 2 /Si interface even after the thermal oxidation. As the temperature increased higher than 1023 K, the Au at the SiO 2 /Si interface diffused into bulk Si, resulting in drastic reduction of AC SPV. On oxidation kinetics between 1023 and 1173 K, Au is thought to act as a catalyst and to promote the SiO 2 growth at the Si surface, resulting in enhanced oxidation.

Collapse of Cr(OH)3/n‐Si Schottky barrier and growth of atomic bridging–type surface photovoltages in Cr‐deposited n‐type Si(001) wafers

“…The AC SPV occurs when a Si semiconductor with a depletion or inversion layer is irradiated with a PB (a negative charge in n‐type Si and/or a positive charge in p‐type Si). Until now, two kinds of AC SPV have been reported, atomic bridging–type and a Schottky barrier type . The atomic bridging–type AC SPV has been postulated to be as follows: if a trivalent Al or Fe, Al 3+ or Fe 3+ replaces the tetravalent Si ion, Si 4+ , in the native oxide or thermally grown oxide by the mechanism of metal‐induced negative oxide charge in the form of a network of (AlOSi) − or (FeOSi) − , demonstrated previously.…”

“…Until now, two kinds of AC SPV have been reported, atomic bridging-type [8][9][10][11][12][13] and a Schottky barrier type. [14][15][16][17][18] The atomic bridging-type AC SPV has been postulated to be as follows: if a trivalent Al or Fe, Al 3+ or Fe 3+ replaces the tetravalent Si ion, Si 4+ , in the native oxide [8][9][10] or thermally grown oxide [12] by the mechanism of metal-induced negative oxide charge [11] in the form of a network of (AlOSi) À or (FeOSi) À , [8][9][10] demonstrated previously.…”

Anomalous Oxide Charge Variation Identified by Alternating Current Surface Photovoltage Method in Cr-Aqueous-Solution-Rinsed p-Type Si(001) Wafers Exposed to Air

“…[9][10][11][12][13][14][15][16][17] This is postulated to be atomic-bridgingtype AC SPV. 18) In contrast, Schottky-barrier-type AC SPV 19) has been reported in Au- [19][20][21] and Cr-aqueoussolution-rinsed n-type Si(001) wafers. 22) AC SPV is essentially caused by charge-induced surface potential, due to either a positive charge in p-type Si or a negative charge in n-type Si when the Si surface is irradiated with a chopped photon beam (PB).…”

“…12,13) As a result, a depletion or inversion layer is generated on the surface. On the other hand, irregular behaviors of Au- [19][20][21] and Cr-induced Schottky-barrier 22) -type AC SPV have been reported in n-type Si(001) wafers. In a previous paper, 22) Cr (Cr 3þ þ 3e À !…”

Formation of Au/n-Si(100) Schottky Barrier Using Au Aqueous Solution

“…Thermal oxide thickness for "Au" and "HF" samples vs oxidation time between 750℃ and 900℃ 11). Reprinted with permission from ref.11.…”