Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-23T15:05:20.775Z Has data issue: false hasContentIssue false
  • English
  • Français

Secondary Electron Emission Contrast of Quantum Wells in GaAs p-i-n Junctions

Published online by Cambridge University Press:  16 March 2009

Enrique Grunbaum ,
Zahava Barkay ,
Yoram Shapira ,
Keith W.J. Barnham ,
David B. Bushnell ,
Nicholas J. Ekins-Daukes ,
Massimo Mazzer  and
Peter Wilshaw
Enrique Grunbaum*
Affiliation:
Department of Physical Electronics, Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
Zahava Barkay
Affiliation:
Wolfson Applied Materials Research Centre, Tel-Aviv University, Tel-Aviv 69978, Israel
Yoram Shapira
Affiliation:
Department of Physical Electronics, Faculty of Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
Keith W.J. Barnham
Affiliation:
Department of Physics, Imperial College of Science, Technology & Medicine, London SW7 2BW, UK
David B. Bushnell
Affiliation:
Department of Physics, Imperial College of Science, Technology & Medicine, London SW7 2BW, UK
Nicholas J. Ekins-Daukes
Affiliation:
Department of Physics, Imperial College of Science, Technology & Medicine, London SW7 2BW, UK
Massimo Mazzer
Affiliation:
Department of Physics, Imperial College of Science, Technology & Medicine, London SW7 2BW, UK
Peter Wilshaw
Affiliation:
Department of Materials, Parks Road, University of Oxford, Oxford OK1 3PH, UK
*
Corresponding author. E-mail: [email protected]
Get access

Abstract

The secondary electron (SE) signal over a cleaved surface of GaAs p-i-n solar cells containing stacks of quantum wells (QWs) is analyzed by high-resolution scanning electron microscopy. The InGaAs QWs appear darker than the GaAsP barriers, which is attributed to the differences in electron affinity. This method is shown to be a powerful tool for profiling the conduction band minimum across junctions and interfaces with nanometer resolution. The intrinsic region is shown to be pinned to the Fermi level. Additional SE contrast mechanisms are discussed in relation to the dopant regions themselves as well as the AlGaAs window at the p-region. A novel method of in situ observation of the SE profile changes resulting from reverse biasing these structures shows that the built-in potential may be deduced. The obtained value of 0.7 eV is lower than the conventional bulk value due to surface effects.

Keywords

high-resolution scanning electron microscopysecondary electronsquantum wellsconductance bandvalence banddopant contrastGaAs
Type
Materials Applications
Information
Microscopy and Microanalysis , Volume 15 , Issue 2 , April 2009 , pp. 125 - 129
Copyright
Copyright © Microscopy Society of America 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Barkay, Z., Grunbaum, E., Shapira, Y., Wilshaw, P., Barnham, K., Bushnell, D.B., Ekins-Daukes, N.J. & Mazzer, M. (2003). High-resolution scanning electron microscopy of dopants in p-i-n junctions with quantum wells. Inst Phys Conf Ser 179, 143–146.Google Scholar
Barkay, Z., Grunbaum, E., Shapira, Y., Wilshaw, P., Barnham, K., Bushnell, D.B., Ekins-Daukes, N.J. & Mazzer, M. (2005). The electric field and dopant distribution in p-i-n structures observe by ionization potential (dopant contrast) microscopy in the HRSEM. Proc Microscopy of Semiconducting Materials XIV, Oxford, UK, Cullis, A.G. & Hutchison, J.L. (Eds.), pp. 503–506. Berlin: Springer Press.Google Scholar
Barnes, J., Nelson, J., Barnham, K.W.J., Roberts, J.S., Pate, M.A., Grey, R., Dosanjh, S.S., Mazzer, M. & Ghiraldo, F. (1996). Characterization of GaAs/InGaAs quantum wells using photocurrent spectroscopy. J Appl Phys 79, 7775–7779.CrossRefGoogle Scholar
Barnham, K.W.J., Ballard, I., Connolly, J.P., Ekins-Daukes, N.J., Kluftinger, B.G., Nelson, J. & Rohr, C. (2002). Quantum well solar cells. Physica 14, 27–36.CrossRefGoogle Scholar
Barnham, K.W.J., Ballard, I., Connolly, J.P., Ekins-Daukes, N.J., Kluftinger, B.G., Nelson, J., Rohr, C. & Mazzer, M. (2000). Recent results on quantum well solar cells. J Mater Sci Mater Electron 11, 531–536.CrossRefGoogle Scholar
Buzzo, M., Ciappa, M. & Fichtner, W. (2006). Imaging and dopant profiling of silicon carbide devices by secondary electron dopant contrast. IEEE Trans Device Mater Reliab 6, 203–212.CrossRefGoogle Scholar
Castaing, R. (1960). Electron probe microanalysis. Adv Electron El Phys 13, 317–386.CrossRefGoogle Scholar
Castelli, R.M., Muller, D.A. & Voyles, P.M. (2003). Dopant mapping for the nanotechnology age. Nat Mater 2, 129–131.CrossRefGoogle Scholar
Chang, T.H.P. & Nixon, W.C. (1967). Electron beam induced potential contrast on unbiased planar transistors. Solid State Electr 10, 701–704.CrossRefGoogle Scholar
Chee, K.W.A., Rodenburg, C. & Humphreys, C.J. (2007). Quantitative dopant profiling in SEM. Proc Microscopy of Semiconducting Materials XV Conf, Cambridge, UK, Cullis, A.G. & Midgley, P.M. (Eds.), pp. 407–410. Berlin: Springer Press.Google Scholar
Ekins-Daukes, N.J., Barnham, K.W.J., Connolly, J.P., Roberts, J.S., Clark, J.C., Hill, G. & Mazzer, M. (1999). Strain-balanced GaAsP/InGaAs quantum well solar cells. Appl Phys Lett 75, 4195–4197.CrossRefGoogle Scholar
El-Gomati, M., Zaggout, F., Jayacody, H., Tear, S. & Wilson, K. (2005). Why is it possible to detect doped regions of semiconductors in low voltage SEM: A review and update. Surf Interface Anal 37, 901–911.CrossRefGoogle Scholar
Elliott, S.L., Broom, R.F. & Humphreys, C.J. (2002). Dopant profiling with the scanning microscope—A study of Si. J Appl Phys 91, 9116–9122.CrossRefGoogle Scholar
Goldstein, J., Newbury, D., Joy, D., Lyman, C., Echlin, P., Lifshin, E., Sawyer, L. & Michael, J. (2003). Scanning Electron Microscopy and X-ray Microanalysis. New York: Plenum Press.CrossRefGoogle Scholar
Joy, D.C. (2008). A database for electron solid interactions. Available at http://web.utk.edu/~srcutk/database.doc.Google Scholar
Kazemian, P., Mentink, S.A.M., Rodenburg, C. & Humphreys, C.J. (2006). High resolution quantitative two-dimensional mapping using energy-filtered secondary electron imaging. J Appl Phys 100, 054901-7.CrossRefGoogle Scholar
Perovic, D.D., Castell, M.R., Howie, A., Lavoie, C., Tiedje, T. & Cole, J.S.W. (1995). Field-emission SEM imaging of compositional and doping layer semiconductor superlattices. Ultramicroscopy 58, 104–113.CrossRefGoogle Scholar
Reimer, L. (1985). Scanning Electron Microscopy: Physics of Image Formation and Microanalysis. Berlin: Springer Verlag Press.CrossRefGoogle Scholar
Schonjahn, C., Humphreys, C.J. & Glick, M. (2002). Energy-filtered imaging in a field-emission scanning electron microscope for dopant mapping in semiconductors. J Appl Phys 92, 7667–7671.CrossRefGoogle Scholar
Schwarzman, A., Grunbaum, E., Strassburg, E., Lepkifker, E., Boag, A. & Rosenwaks, Y. (2005). Nanoscale potential distribution across multi-quantum well structures: Kelvin probe force microscopy and secondary electron imaging. J Appl Phys 98, 084310-1-4.CrossRefGoogle Scholar
Sealy, C.P., Castell, M.R. & Wilshaw, P.R. (2000). Mechanism for secondary electron dopant contrast in the SEM. J Electron Microsc 49, 311–321.CrossRefGoogle ScholarPubMed
Sze, S.M. (1981). Physics of Semiconductor Devices, 2nd ed. New York: John Wiley.Google Scholar
Venables, D., Jain, H. & Collins, D.C. (1998). Secondary electron imaging as a two-dimensional dopant profiling technique: Review and update. J Vac Sci Technol B 16, 362–366.CrossRefGoogle Scholar