TY - JOUR
T1 - Energy level and band alignment for GaAs - Alkylthiol monolayer - Hg junctions from electrical transport and photoemission experiments
AU - Neshar, Guy
AU - Vilan, Ayelet
AU - Cohen, Hagai
AU - Cahen, David
AU - Amy, Fabrice
AU - Chan, Calvin
AU - Hwang, Jaehyung
AU - Kahn, Antoine
PY - 2006/7/27
Y1 - 2006/7/27
N2 - A series of p- and n-GaAs-S-CnH2n+1 ∥ Hg junctions are prepared, and the electronic transport through them is measured. From current-voltage measurements, we find that, for n-GaAs, transport occurs by both thermionic emission and tunneling, with the former dominating at low forward bias and the latter dominating at higher forward bias. For p-GaAs, tunneling dominates at all bias voltages. By combining the analysis of the transport data with results from direct and inverse photoemission spectroscopy, we deduce an energy band diagram of the system, including the tunnel barrier and, with this barrier and within the Simmons tunneling model, extract an effective mass value of 1.5-1.6me for the electronic carriers that cross the junctions, We find that transport is well-described by lowest unoccupied and highest occupied states at 1.3-1.4 eV above and 2.0-2.2 eV below the Fermi level. At the same time, the photoemission data indicate that there are continua of states from the conduction band minimum and the valence band maximum, the density of which varies with energy. On the basis of our results, it appears likely that, for both types of junctions, electrons are the main carrier type, although holes may contribute significantly to the transport in the p-GaAs system.
AB - A series of p- and n-GaAs-S-CnH2n+1 ∥ Hg junctions are prepared, and the electronic transport through them is measured. From current-voltage measurements, we find that, for n-GaAs, transport occurs by both thermionic emission and tunneling, with the former dominating at low forward bias and the latter dominating at higher forward bias. For p-GaAs, tunneling dominates at all bias voltages. By combining the analysis of the transport data with results from direct and inverse photoemission spectroscopy, we deduce an energy band diagram of the system, including the tunnel barrier and, with this barrier and within the Simmons tunneling model, extract an effective mass value of 1.5-1.6me for the electronic carriers that cross the junctions, We find that transport is well-described by lowest unoccupied and highest occupied states at 1.3-1.4 eV above and 2.0-2.2 eV below the Fermi level. At the same time, the photoemission data indicate that there are continua of states from the conduction band minimum and the valence band maximum, the density of which varies with energy. On the basis of our results, it appears likely that, for both types of junctions, electrons are the main carrier type, although holes may contribute significantly to the transport in the p-GaAs system.
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U2 - 10.1021/jp062181i
DO - 10.1021/jp062181i
M3 - Article
C2 - 16854143
AN - SCOPUS:33746912736
SN - 1520-6106
VL - 110
SP - 14363
EP - 14371
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 29
ER -