Relevance of surface electronic structure for high frequency dispersion on n-type accumulation capacitance
皮敦文1*, 鄭秋平2, 洪銘輝3, 郭瑞年4
1Science, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
2Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Chiayi, Taiwan
3Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, Taiwan
4Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
* presenting author:Tun-Wen Pi, email:pi@nsrrc.org.tw
The investigation tackles the origin of long-puzzled high frequency dispersion on the accumulation region of capacitance-voltage characteristics in n-type GaAs-based metal-oxide-semiconductor. Probed adatoms of high Pauli electronegativity as Ag and Au were deposited onto as-grown 2-GaAs(001)-2x4 surfaces studied by high-resolution core-level synchrotron radiation photoemission. The noble-metal adatoms in the submonolayer coverage bond intimately with the GaAs surface atoms without causing surface disruption. The supposed charge acceptors of the adatoms anomalously donate charge onto the contacted As/Ga atoms. The GaAs surface atoms then tend to drain electrons, and if not properly passivated would trap those accumulated at the oxide and semiconductor interface under positive bias voltage. Remnant of unpassivated surface As atoms indeed exists in the Al2O3/n-GaAs(001)-2x4 as well as n-GaAs(001)-4x6 interfaces, thereby causing high frequency dispersion.


Keywords: high k, GaAs, synchrotron radiation photoemission, core-level spectra