Determination of the electron distribution in thin barrier AlGaAs/GaAs superlattices by capacitance-voltage profiling

Electron density distribution in uniformly doped AlGaAs/GaAs superlattices with respective layer thicknesses 1.5/10 nm and a different number of quantum wells was investigated. Experimental samples containing 3, 5 and 25 periods with the same layer parameters were grown by molecular beam epitaxy. Capacitance-voltage profiling was used to determine the carrier concentration profiles in the structures both numerically and experimentally. During the analysis of experimental capacitance-voltage characteristics it was found that the maximum electron concentration increases with an increase in the number of quantum wells starting from 7,1∙10¹⁶ сm^–3 for 3 wells up to 9,2∙10¹⁶ сm^–3 for 25 wells with overall superlattice doping level of 10¹⁷ сm^–3. In some samples saturation areas are observed on the concentration profiles, that are associated with the region of superlattice. Concentration values, obtained from computer modeling, correspond to the experimental data with an error of less than 10 %. Capacitance-voltage profiling is a suitable technique for determining the carrier concentration profiles in thin barrier superlattices. Despite the fact that the method provides distribution of the «apparent» carrier concentration profile, it can be used to estimate the dopant atoms distribution in the strongly coupled quantum well heterostructures.

1. Del Alamo J.A. Nanometre-scale electronics with III–V compound semiconductors. Nature, 2011, vol. 479, no. 7373, pp. 317–323. https://doi.org/10.1038/nature10677

2. Fox M., Ispasoiu R. Quantum wells, superlattices, and band-gap engineering. Springer Handbook of Electronic and Photonic Materials. Cham, Springer International Publishing, 2017. https://doi.org/10.1007/978-3-319-48933-9_40

3. Goray L., Pirogov E., Sobolev M., Ilkiv I., Dashkov A., Nikitina E., Ubyivovk E., Gerchikov L., Ipatov A., Vainer Y., Svechnikov M., Yunin P., Chkhalo N., Bouravlev A. Matched characterization of super-multiperiod superlattices. Journal of Physics D: Applied Physics, 2020, vol. 53, no. 45, pp. 455103. https://doi.org/10.1088/1361-6463/aba4d6

4. Mokhov D.V., Berezovskaya T.N., Kuzmenkov A.G., Maleev N.A., Timoshnev S.N., Ustinov V.M. Precision calibration of the silicon doping level in gallium arsenide epitaxial layers. Technical Physics Letters, 2017, vol. 43, no. 10, pp. 909–911. https://doi.org/10.1134/S1063785017100091

5. Schroder D.K. Semiconductor Material and Device Characterization. 3rd ed. Piscataway, Hoboken, NJ, Wiley-IEEE Press, 2015, 800 с.

6. Tschirner B.M., Morier-Genoud F., Martin D., Reinhart F.K. Capacitance-voltage profiling of quantum well structures. Journal of Applied Physics, 1996, vol. 79, no. 9, pp. 7005–7013. https://doi.org/10.1063/1.361466

7. Bobylev B.A., Kovalevskaja T.E., Marchishin I.V., Ovsyuk V.N. Capacitance-voltage profiling of multiquantum well structures. Solid-State Electronics, 1997, vol. 41, no. 3, pp. 481–486. https://doi.org/10.1016/S0038-1101(96)00186-4

8. Chiquito A.J., Pusep Yu.A., Mergulhão S., Galzerani J.C. Carrier confinement in an ultrathin barrier GaAs/AlAs superlattice probed by capacitance-voltage measurements. Physica E: Low-dimensional Systems and Nanostructures, 2002, vol. 13, no. 1, pp. 36–42. https://doi.org/10.1016/S1386-9477(01)00222-3

9. Gerchikov L.G., Dashkov A.S., Goray L.I., Bouravleuv A.D. Development of the design of super-multiperiod structures grown by molecular-beam epitaxy and emitting in the terahertz range. Journal of Experimental and Theoretical Physics, 2021, vol. 133, no. 2, pp. 161–168. https://doi.org/10.1134/S1063776121070037

10. Varache R., Leendertz C., Gueunier-Farret M.E., Haschke J., Muñoz D., Korte L. Investigation of selective junctions using a newly developed tunnel current model for solar cell applications. Solar Energy Materials and Solar Cells, 2015, vol. 141, pp. 14–23. https://doi.org/10.1016/j.solmat.2015.05.014