Skip to main content Accessibility help

Surface-induced effects in GaN nanowires

  • Raffaella Calarco (a1), Toma Stoica (a2), Oliver Brandt (a3) and Lutz Geelhaar (a3)


Semiconductor nanowires (NWs) are characterized by an extraordinarily large surface-to-volume ratio. Consequently, surface effects are expected to play a much larger role than in thin films. Here, we review a research focused on the impact of the surface on the electrical and optical properties of catalyst-free GaN NWs with growth direction <0001>. Using a combination of complementary experimental techniques, it has been shown that the Fermi level is pinned at the NW sidewall surfaces, resulting in internal electric fields and in full depletion for NWs below a critical diameter. Deoxidation of the surfaces unpins the Fermi level, leading to enhanced radiative recombination of excitons. Prominent absorption below the bandgap is caused by the Franz-Keldysh effect. Close to the surface, the ionization energy of donors is reduced. The consideration of surface-induced effects is mandatory for an understanding of the physical properties of NWs as well as their application in devices.


Corresponding author

a)Address all correspondence to this author. e-mail:


Hide All

This section of Journal of Materials Research is reserved for papers that are reviews of literature in a given area.



Hide All
1.Lieber, C.M. and Wang, Z.L.: Functional nanowires. MRS Bull. 32, 99 (2007).
2.Yang, P., Yan, R., and Fardy, M.: Semiconductor nanowire: What’s next? Nano Lett. 10, 1529 (2010).
3.Glas, F.: Critical dimensions for the plastic relaxation of strained axial heterostructures in free-standing nanowires. Phys. Rev. B 74, 121302(R) (2006).
4.Bjork, M.T., Ohlsson, B.J., Sass, T., Persson, A.I., Thelander, C., Magnusson, M.H., Deppert, K., Wallenberg, L.R., and Samuelson, L.: One-dimensional heterostructures in semiconductor nanowhiskers. Appl. Phys. Lett. 80, 1058 (2002).
5.Patolsky, F., Zheng, G., and Lieber, C.M.: Nanowire sensors for medicine and the life sciences. Nanomedicine 1, 51 (2006).
6.Ramgir, N.S., Yang, Y., and Zacharias, M.: Nanowire-based sensors. Small 6, 1705 (2010).
7.Yoshizawa, M., Kikuchi, A., Mori, M., Fujita, N., and Kishino, K.: Growth of self-organized GaN nanostructures on Al2O3 by RF-radical source molecular beam epitaxy. Jpn. J. Appl. Phys. 36, L459 (1997).
8.Calleja, E., Sánchez-Garciá, M.A., Sánchez, F.J., Calle, F., Naranjo, F.B., Muñoz, E., Jahn, U., and Ploog, K.: Luminescence properties and defects in GaN nanocolumns grown by molecular beam epitaxy. Phys. Rev. B 62, 16826 (2000).
9.Bertness, K.A., Roshko, A., Sanford, N.A., Barker, J.M., and Davydov, A.V.: Spontaneously grown GaN and AlGaN nanowires. J. Cryst. Growth 287, 522 (2006).
10.Calarco, R., Meijers, R.J., Debnath, R.K., Stoica, T., Sutter, E., and Lüth, H.: Nucleation and growth of GaN nanowires on Si(111) performed by molecular beam epitaxy. Nano Lett. 7, 2248 (2007).
11.Consonni, V., Knelangen, M., Geelhaar, L., Trampert, A., and Riechert, H.: Nucleation mechanisms of epitaxial GaN nanowires: Origin of their self-induced formation and initial radius. Phys. Rev. B 81, 085310 (2010).
12.Gotschke, T., Schumann, T., Limbachl, F., Stoica, T., and Calarco, R.: Influence of the adatom diffusion on selective growth of GaN nanowire regular arrays. Appl. Phys. Lett. 98, 103102 (2011).
13.Hersee, S.D., Sun, X., and Wang, X.: The controlled growth of GaN nanowires. Nano Lett. 6, 1808 (2006).
14.Chèze, C., Geelhaar, L., Brandt, O., Weber, W.M., Riechert, H., Münch, S., Rothemund, R., Reitzenstein, S., Forchel, A., Kehagias, T., Komninou, P., Dimitrakopoulos, G.P., and Karakostas, T.: Direct comparison of catalyst-free and catalyst-induced GaN nanowires. Nano Res. 3, 528 (2010).
15.Geelhaar, L., Chèze, C., Jenichen, B., Brandt, O., Pfüller, C., Münch, S., Rothemund, R., Reitzenstein, S., Forchel, A., Kehagias, Th., Komninou, Ph., Dimitrakopulos, G.P., Karakostas, Th., Lari, L., Chalker, P.R., Gass, M.H., and Riechert, H.: Properties of GaN nanowires grown by molecular beam epitaxy. IEEE J. Sel. Top. Quantum Electron. (August 2011, in press).
16.Kuykendall, T., Pauzauskie, P., Lee, S., Zhang, Y., Goldberger, J., and Yang, P.: Metalorganic chemical vapor deposition route to GaN nanowires with triangular cross sections. Nano Lett. 3, 1063 (2003).
17.Qian, F., Li, Y., Gradecak, S., Wang, D., Barrelet, C.J., and Lieber, C.M.: Gallium nitride-based nanowire radial heterostructures for nanophotonics. Nano Lett. 4, 1975 (2004).
18.Wang, G.T., Talin, A.A., Werder, D.J., Creighton, J.R., Lai, E., Anderson, R.J., and Arslan, I.A.: Highly aligned, template-free growth and characterization of vertical GaN nanowires on sapphire by metal–organic chemical vapour deposition. Nanotechnology 17, 5773 (2006).
19.Chen, C-C., Yeh, C-C., Chen, C-H., Yu, M-Y., Liu, H-L., Wu, J-J., Chen, K-H., Chen, L-C., Peng, J-Y., and Chen, Y-F.: Catalytic growth and characterization of gallium nitride nanowires. Am. Chem. Soc. 123, 2791 (2001).
20.Chen, R-S., Chen, H-Y., Lu, C-Y., Chena, K-H., Chen, C-P., Chen, L-C., and Yang, Y-J.: Ultrahigh photocurrent gain in m-axial GaN nanowires. Appl. Phys. Lett. 91, 223106 (2007).
21.Long, J.P., Simpkins, B.S., Rowenhorst, D.J., and Pehrsson, P.E.: Far-field imaging of optical second-harmonic generation in single GaN nanowires. Nano Lett. 7, 831 (2007).
22.Kocan, M., Rizzi, A., Lüth, H., Keller, S., and Mishra, U.K.: Surface potential at as-grown GaN(0001) MBE layers. Phys. Status Solidi B 234, 773 (2002).
23.Calarco, R., Marso, M., Richter, T., Aykanat, A.I., Meijers, R., Hart, A.v.d., Stoica, T., and Lüth, H.: Size-dependent photoconductivity in MBE grown GaN-nanowires. Nano Lett. 5, 981 (2005).
24.Richter, T., Lüth, H., Meijers, R., Calarco, R., and Marso, M.: Determining doping concentration in GaN nanowires by opto-electrical characterization. Nano Lett. 8, 3056 (2008).
25.Chen, H-Y., Chen, R-S., Chang, F-C., Chen, L-C., Chen, K-H., and Yang, Y-J.: Size-dependent photoconductivity and dark conductivity of m-axial GaN nanowires with small critical diameter. Appl. Phys. Lett. 95, 143123 (2009).
26.Talin, A.A., Swartzentruber, B.S., Léonard, F., Wang, X., and Hersee, S.D.: Unusually strong space-charge-limited current in thin wires. Phys. Rev. Lett. 101, 076802 (2008).
27.Talin, A.A., Swartzentruber, B.S., Léonard, F., Wang, X., and Hersee, S.D.: Electrical transport in GaN nanowires grown by selective epitaxy. J. Vac. Sci. Technol., B 27, 2040 (2009).
28.Hirsch, M.T., Wolk, J.A., Walukiewicz, W., and Haller, E.E.: Persistent photoconductivity in n-type GaN. Appl. Phys. Lett. 71, 1098 (1997).
29.Qiu, C.H. and Pankove, J.I.: Deep levels and persistent photoconductivity in GaN thin films. Appl. Phys. Lett. 70, 1983 (1997).
30.Lin, Y., Yang, H.C., and Chen, Y.F.: Optical quenching of the photoconductivity in n-type GaN. J. Appl. Phys. 87, 3404 (2000).
31.Dalpian, G.M. and Chelikowsky, J.R.: Self-purification in semiconductor nanocrystals. Phys. Rev. Lett. 96, 226802 (2006).
32.Carter, D.J. and Stampfl, C.: Atomic and electronic structure of single and multiple vacancies in GaN nanowires from first-principles. Phys. Rev. B 79, 195302 (2009).
33.Jeganathan, K., Debnath, R.K., Meijers, R., Stoica, T., Calarco, R., Grützmacher, D., and Lüth, H.: Raman scattering of phonon-plasmon coupled modes in self-assembled GaN nanowires. J. Appl. Phys. 105, 123707 (2009).
34.Stoica, T. and Calarco, R.: Doping of III-nitride nanowires grown by molecular beam epitaxy. IEEE J. Sel. Top. Quantum Electron. (August 2011, in press).
35.Sanford, N.A., Blanchard, P.T., Bertness, K.A., Mansfield, L., Schlager, J.B., Sanders, A.W., Roshko, A., Burton, B.B., and George, S.M.: Steady-state and transient photoconductivity in c-axis GaN nanowires grown by nitrogen-plasma-assisted molecular-beam epitaxy. J. Appl. Phys. 107, 034318 (2010).
36.Simpkins, B.S., Mastro, M.A., Eddy, C.R. Jr., and Pehrsson, P.E.: Surface depletion effects in semiconducting nanowires. J. Appl. Phys. 103, 104313 (2008).
37.Mansfield, L.M., Bertness, K.A., Blanchard, P.T., Harvey, T.E., Sanders, A.W., and Sanford, N.A.: GaN nanowire carrier concentration calculated from light and dark resistance measurements. J. Electron. Mater. 38, 495 (2009).
38.Simpkins, B.S., Mastro, M.A., Eddy, C.R. Jr., and Pehrsson, P.E.: Surface-induced transients in gallium nitride nanowires. J. Phys. Chem. C 113, 9480 (2009).
39.Camacho, J., Santos, P., Alsina, F., Ramsteiner, M., Ploog, K., Cantarero, A., Obloh, H., and Wagner, J.: Modulation of the electronic properties of GaN films by surface acoustic waves. J. Appl. Phys. 94, 1892 (2003).
40.Pedrós, J., Takagaki, Y., Ive, T., Ramsteiner, M., Brandt, O., Jahn, U., Ploog, K.H., and Calle, F.: Exciton impact-ionization dynamics modulated by surface acoustic waves in GaN. Phys. Rev. B 75, 115305 (2007).
41.Pfüller, C., Brandt, O., Grosse, F., Flissikowski, T., Chèze, C., Consonni, V., Geelhaar, L., Grahn, H.T., and Riechert, H.: Unpinning the Fermi level in GaN nanowires by ultraviolet radiation. Phys. Rev. B 82, 045320 (2010).
42.Dobrokhotov, V., McIlroy, D.N., Grant Norton, M., Abuzir, A., Yeh, W.J., Stevenson, I., Pouy, R., Bochenek, J., Cartwright, M., Wang, L., Dawson, J., Beaux, M., and Bervena, C.: Principles and mechanisms of gas sensing by GaN nanowires functionalized with gold nanoparticles. J. Appl. Phys. 99, 104302 (2006).
43.Lim, W., Wright, J.S., Gila, B.P., Johnson, J.L., Ural, A., Anderson, T., Ren, F., and Pearton, S.J.: Room temperature hydrogen detection using Pd-coated GaN nanowires. Appl. Phys. Lett. 93, 072109 (2008).
44.Simpkins, B.S., McCoy, K.M., Whitman, L.J., and Pehrsson, P.E.: Fabrication and characterization of DNA-functionalized GaN nanowires. Nanotechnology 18, 355301 (2007).
45.Guo, D.J., Abdulagatov, A.I., Rourke, D.M., Bertness, K.A., George, S.M., Lee, Y.C., and Tan, W.: GaN nanowire functionalized with atomic layer deposition techniques for enhanced immobilization of biomolecules. Langmuir 26, 18382 (2010).
46.Chen, C-P., Ganguly, A., Lu, C-Y., Chen, T-Y., Kuo, C-C., Chen, R-S., Tu, W-H., Fischer, W.B., Chen, K-H., and Chen, L-C.: Ultrasensitive in situ label-free DNA detection using a GaN nanowire-based extended-gate field-effect-transistor sensor. Anal. Chem. 83, 1938 (2011).
47.Cavallini, A., Polenta, L., Rossi, M., Stoica, T., Calarco, R., Meijers, R.J., Richter, T., and Lüth, H.: Franz-Keldysh effect in GaN nanowires. Nano Lett. 7, 2166 (2007).
48.Thillosen, N., Sebald, K., Hardtdegen, H., Meijers, R., Calarco, R., Montanari, S., Kaluza, N., Gutowski, J., and Lüth, H.: The state of strain in single GaN nanocolumns as derived from micro-photoluminescence measurements. Nano Lett. 6, 704 (2006).
49.Stoica, T., Sutter, E., Meijers, R.J., Debnath, R.K., Calarco, R., Lüth, H., and Grützmacher, D.: Interface and wetting layer effect on the catalyst-free nucleation and growth of GaN nanowires. Small 4, 751 (2008).
50.Armstrong, A., Li, Q., Bogart, K.H.A., Lin, Y., Wang, G.T., and Talin, A.A.: Deep level optical spectroscopy of GaN nanorods. J. Appl. Phys. 106, 053712 (2009).
51.Armstrong, A., Li, Q., Lin, Y., Talin, A.A., and Wang, G.T.: GaN nanowire surface state observed using deep level optical spectroscopy. Appl. Phys. Lett. 96, 163106 (2010).
52.Cavallini, A., Polenta, L., Rossi, M., Richter, T., Marso, M., Meijers, R., Calarco, R., and Lüth, H.: Defect distribution along single GaN nanowhiskers. Nano Lett. 6, 1548 (2006).
53.Polenta, L., Cavallini, A., Rossi, M., Calarco, R., Marso, M., Stoica, T., Meijers, R., Richter, T., and Lüth, H.: Investigation on localized states in GaN nanowires. ACS Nano 2, 287 (2008).
54.Brandt, O., Pfüller, C., Chèze, C., Geelhaar, L., and Riechert, H.: Sub-meV linewidth of excitonic luminescence in single GaN nanowires: Direct evidence for surface excitons. Phys. Rev. B 81, 045302 (2010).
55.Pfüller, C., Brandt, O., Flissikowski, T., Chèze, C., Geelhaar, L., Grahn, H.T., and Riechert, H.: Statistical analysis of excitonic transitions in single, free-standing GaN nanowires: Probing impurity incorporation in the Poissonian limit. Nano Res. 3, 881 (2010).
56.Levine, J.D.: Nodal hydrogenic wave functions of donors on semiconductor surfaces. Phys. Rev. 140, A586 (1965).
57.Diarra, M., Niquet, Y.-M., Delerue, C., and Allan, G.: Ionization energy of donor and acceptor impurities in semiconductor nanowires: Importance of dielectric confinement. Phys. Rev. B 75, 045301 (2007).
58.Corfdir, P., Lefebvre, P., Ristić, J., Valvin, P., Calleja, E., Trampert, A., Ganière, J.-D., and Deveaud-Plédran, B.: Time-resolved spectroscopy on GaN nanocolumns grown by plasma-assisted molecular-beam epitaxy on Si substrates. J. Appl. Phys. 105, 013113 (2009).
59.Fernández-Serra, M.V., Adessi, Ch., and Blasé, X.: Surface segregation and backscattering in doped silicon nanowires. Phys. Rev. Lett. 96, 166805 (2006).
60.Li, Q. and Wang, G.T.: Spatial distribution of defect luminescence in GaN nanowires. Nano Lett. 10, 1554 (2010).
61.Wang, Z., Li, J., Gao, F., and Weber, W.J.: Defects in gallium nitride nanowires: First-principles calculations. J. Appl. Phys. 108, 044305 (2010).


Surface-induced effects in GaN nanowires

  • Raffaella Calarco (a1), Toma Stoica (a2), Oliver Brandt (a3) and Lutz Geelhaar (a3)


Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed