Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5425150 | Surface Science | 2007 | 4 Pages |
Scanning tunneling microscopy luminescence (STML) was induced from the nanometer scale surfaces of cleaved n-type and p-type GaAs(1Â 1Â 0) wafers by using of an ITO-coated optical fiber probe in an ultrahigh-vacuum chamber. The STML from n-type GaAs(1Â 1Â 0) surface was induced under negative sample bias when the applied bias exceeds a threshold voltage around â1.5Â V. Whereas the STML from p-type GaAs(1Â 1Â 0) surface was induced under positive sample bias when the applied bias exceeds a threshold voltage around +1.5Â V. The excitation energies at the threshold voltages are consistent with the band gap of GaAs (1.42Â eV) at 295Â K. The typical quantum efficiencies for n-type and p-type GaAs are about 3Â ÃÂ 10â5 and 2Â ÃÂ 10â4 photons/electron, respectively. The observed STML from are attributed to a radiative recombination of electron-hole pairs generated by a hole injection for n-type GaAs under negative sample bias and an electron injection for p-type GaAs under positive sample bias, respectively.