[paper] GaN/AlGaN 2DEGs grown on bulk GaN

Luisa Krückeberg¹,  Steffen Wirth²,  Victor V. Solovyev³, Andreas Großer¹, Igor V. Kukushkin^3,4,  Thomas Mikolajick^1,5, and  Stefan Schmult⁵

Quantum and transport lifetimes in optically induced GaN/AlGaN 2DEGs

grown on bulk GaN

Journal of Vacuum Science and Technology B 38, 042203 (2020)

DOI: 10.1116/1.5145198

¹NaMLab GmbH, Dresden (D)
²Max-Planck-Institute for Chemical Physics of Solids, Dresden (D)
³Institute of Solid State Physics RAS, Moscow (RU)
⁴National Research University Higher School of Economics, Moscow (RU)
⁵Institute of Semiconductors and Microsystems, TU Dresden, Dresden (D)

ABSTRACT A two-dimensional electron gas (2DEG) is absent in ultrapure GaN/Al0.06Ga0.94N heterostructures grown by molecular beam epitaxy on bulk GaN at 300 K and in the dark. However, such a 2DEG can be generated by UV illumination and persists at low temperature after blanking the light. Under steady UV illumination as well as under persistence conditions, pronounced quantum transport with Shubnikov–de Haas oscillations commencing below 2 T is observed. The low temperature 2DEG mobility amounts to only ∼20 000 cm2/V s, which is much lower than predicted for the dominant scattering mechanisms in GaN/AlGaN heterostructures grown on GaN with low threading dislocation density. A rather small ratio of the transport and quantum lifetimes τt/τq of ∼10 points at elastic scattering events limiting both the transport and quantum lifetimes.

FIG. (a) Photograph of a Hall bar device and (b) its two-terminal resistance R2pt at stabilized temperatures between 120 and 135K. The estimated UV power during illumination is in the low nanowatts range, which does not result in a saturation of R2pt at these specific temperatures. The recombination time, i.e., the time until disappearance of the 2DEG, increases significantly at 120K. At 100 K, no increase in R2pt is observed after switching off the illumination.

ACKNOWLEDGMENTS The NaMLab gGmbH part was financially supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project No. 405782347, the German Federal Ministry of Education and Research—BMBF (Project “ZweiGaN,” No. 16ES0145K), and the German Federal Ministry of Economics and Technology—BMWi (Project No. 03ET1398B). V.V.S. and I.V.K. acknowledge the support from the Russian Science Foundation (Grant No. 19-42-04119). The TU Dresden part of the work was partially funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project No. 348524434.