Abstract
Surface photovoltage (SPV) transient provides a non-destructive, contact-free method for characterization of semiconductor surfaces. Here we study SPV-transients of differently cleaned, heavily doped epiready GaAs wafers. After a rapid initial part the transient shows a very slow decay taking place in 100 - 1000 s time scale. Chemical NH4OH:H2O 2:H2O cleaning and atomic hydrogen UHV cleaning are applied. SPV-transients are measured by Kelvin probe in normal atmospheric conditions. A large signal surface trapping model is developed which includes both majority and minority carrier processes and covers the whole light on, steady state, light off sequence. Model fitting allows band bending, energy and density of surface states as well as electron and hole capture cross-sections to be extracted. The results show that the traps are electronic states in thin oxide layer covering the samples. This conclusion is based on the finding that the capture cross-sections are very small, in the range 10-19 - 10-26 cm2, which calls tunneling for explanation. This indicates that after cleaning the oxide layer is rapidly re-grown in laboratory atmosphere in less than 30 min. Typical band bendings are 0.6 - 0.8 eV, trap energies are slightly above the mid-gap and the density of occupied trap states is around 5×1012 cm-2 at thermal equilibrium.
| Original language | English |
|---|---|
| Title of host publication | Proceedings of Spie - The International Society for Optical Engineering |
| Subtitle of host publication | Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV |
| Publisher | International Society for Optics and Photonics SPIE |
| Volume | 6800 |
| ISBN (Print) | 978-081946971-7 |
| DOIs | |
| Publication status | Published - 31 Mar 2008 |
| MoE publication type | A4 Article in a conference publication |
| Event | Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV - Canberra, Australia Duration: 5 Dec 2007 → 7 Dec 2007 |
Conference
| Conference | Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV |
|---|---|
| Country | Australia |
| City | Canberra |
| Period | 5/12/07 → 7/12/07 |
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Keywords
- Kelvin probe
- Slow traps
- Surface photovoltage transient
- Tunneling assisted trapping
Cite this
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Characterization of epiready n+-GaAs (100) surfaces by SPV-transient. / Sinkkonen, Juha (Corresponding author); Novikov, Sergey; Varpula, Aapo; Haapamaa, J.
Proceedings of Spie - The International Society for Optical Engineering: Device and Process Technologies for Microelectronics, MEMS, Photonics, and Nanotechnology IV. Vol. 6800 International Society for Optics and Photonics SPIE, 2008. 68001D.Research output: Chapter in Book/Report/Conference proceeding › Conference article in proceedings › Scientific › peer-review
TY - GEN
T1 - Characterization of epiready n+-GaAs (100) surfaces by SPV-transient
AU - Sinkkonen, Juha
AU - Novikov, Sergey
AU - Varpula, Aapo
AU - Haapamaa, J.
PY - 2008/3/31
Y1 - 2008/3/31
N2 - Surface photovoltage (SPV) transient provides a non-destructive, contact-free method for characterization of semiconductor surfaces. Here we study SPV-transients of differently cleaned, heavily doped epiready GaAs wafers. After a rapid initial part the transient shows a very slow decay taking place in 100 - 1000 s time scale. Chemical NH4OH:H2O 2:H2O cleaning and atomic hydrogen UHV cleaning are applied. SPV-transients are measured by Kelvin probe in normal atmospheric conditions. A large signal surface trapping model is developed which includes both majority and minority carrier processes and covers the whole light on, steady state, light off sequence. Model fitting allows band bending, energy and density of surface states as well as electron and hole capture cross-sections to be extracted. The results show that the traps are electronic states in thin oxide layer covering the samples. This conclusion is based on the finding that the capture cross-sections are very small, in the range 10-19 - 10-26 cm2, which calls tunneling for explanation. This indicates that after cleaning the oxide layer is rapidly re-grown in laboratory atmosphere in less than 30 min. Typical band bendings are 0.6 - 0.8 eV, trap energies are slightly above the mid-gap and the density of occupied trap states is around 5×1012 cm-2 at thermal equilibrium.
AB - Surface photovoltage (SPV) transient provides a non-destructive, contact-free method for characterization of semiconductor surfaces. Here we study SPV-transients of differently cleaned, heavily doped epiready GaAs wafers. After a rapid initial part the transient shows a very slow decay taking place in 100 - 1000 s time scale. Chemical NH4OH:H2O 2:H2O cleaning and atomic hydrogen UHV cleaning are applied. SPV-transients are measured by Kelvin probe in normal atmospheric conditions. A large signal surface trapping model is developed which includes both majority and minority carrier processes and covers the whole light on, steady state, light off sequence. Model fitting allows band bending, energy and density of surface states as well as electron and hole capture cross-sections to be extracted. The results show that the traps are electronic states in thin oxide layer covering the samples. This conclusion is based on the finding that the capture cross-sections are very small, in the range 10-19 - 10-26 cm2, which calls tunneling for explanation. This indicates that after cleaning the oxide layer is rapidly re-grown in laboratory atmosphere in less than 30 min. Typical band bendings are 0.6 - 0.8 eV, trap energies are slightly above the mid-gap and the density of occupied trap states is around 5×1012 cm-2 at thermal equilibrium.
KW - Kelvin probe
KW - Slow traps
KW - Surface photovoltage transient
KW - Tunneling assisted trapping
UR - http://www.scopus.com/inward/record.url?scp=41149118633&partnerID=8YFLogxK
U2 - 10.1117/12.759378
DO - 10.1117/12.759378
M3 - Conference article in proceedings
AN - SCOPUS:41149118633
SN - 978-081946971-7
VL - 6800
BT - Proceedings of Spie - The International Society for Optical Engineering
PB - International Society for Optics and Photonics SPIE
ER -