High-speed nanowire LED in the blue/green spectral range

• Applicants: Professor Dr. Gerd Bacher; Dr.-Ing. Werner Prost
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 387904162

• Final Report Year: 2023

Final Report Abstract

We developed a new epitaxy process for core-shell p-i-n-nanorod LEDs based on nitrides. This includes a technology for selectively growing metal-polar nanorods on Si templates and the development of a suitable growth model. Homogeneous InGaN quantum wells on non-polar mplanes have been realized. Local optical spectroscopy and TEM experiments show that the quantum well emission is purely stemming from the field-free m-facets. This contrasts with reference data on nanorods grown on sapphire, where local In-accumulation leads to a multi-color and voltage dependent emission from edges and tips of the nanorods. Spatially resolved electrical characterization of the contact between the GaN cores and the Si (111) substrate indicates a relatively low resistance in spite of the quite thick AlN interlayers. Die achieved current densities > 10 µA/cm² should in principle enable high frequency operation of the devices. This proves that the AlN buffer layer between Si (111) and the n-GaN core, which is important for avoiding the melt-back effect, is not a fundamental drawback of our approach. A remaining challenge is a HF-compatible contacting of the nanorod array, which until now prevented the achievement of a cutoff frequency of 2 GHz. Electro-optical studies of reference nanorod LEDs on sapphire indicate that besides leakage current tunneling losses may limit the external quantum efficiency of such devices, in particular in the low injection regime.

Publications

• Low injection losses in InGaN/GaN LEDs: The correlation of photoluminescence, electroluminescence, and photocurrent measurements. Journal of Applied Physics, 123(21), 214502.
  Quitsch, Wolf-Alexander; Sager, Daniel; Loewenich, Moritz; Meyer, Tobias; Hahn, Berthold & Bacher, Gerd
  
• Polarity‐ and Site‐Controlled Metal Organic Vapor Phase Epitaxy of 3D‐GaN on Si(111). physica status solidi (b), 255(5).
  Blumberg, Christian; Grosse, Simon; Weimann, Nils; Tegude, Franz‐Josef & Prost, Werner
  
• Mask-less MOVPE of arrayed n-GaN nanowires on site- and polarity-controlled AlN/Si templates. CrystEngComm, 21(48), 7476-7488.
  Blumberg, C.; Wefers, F.; Tegude, F.-J.; Weimann, N. & Prost, W.
  
• Site- and polarity-controlled GaN nanowires on silicon for high-speed LEDs, Nanowire Week Sep. 25-27, 2019, Pisa, Italien.
  C. Blumberg, F. Wefers, J. Meier, N. Weimann, G. Bacher & W. Prost
  
• Site- and polarity-controlled GaN NW on Silicon for high-speed LEDs, PDI Topical Workshop Epitaxial III-Nitride Semiconductor Nanowires, Berlin, Germany, June 6-7, 2019.
  C. Blumberg, F. Wefers, J. Meier, N. Weimann, G. Bacher & W. Prost
  
• Site- and polarity-controlled MOVPE of InGaN/GaN nanowires for high-speed LEDs on silicon substrates, International Conference on Nitride Semiconductors, July 7-12, 2019, Bellevue, Washington, USA
  C. Blumberg, F. Wefers, J. Meier, N. Weimann, G. Bacher & W. Prost
  
• A systematic study of Ga- and N-polar GaN nanowire–shell growth by metal organic vapor phase epitaxy. CrystEngComm, 22(33), 5522-5532.
  Blumberg, Christian; Häuser, Patrick; Wefers, Fabian; Jansen, Dennis; Tegude, Franz-Josef; Weimann, Nils & Prost, Werner
  
• Spatially controlled VLS epitaxy of gallium arsenide nanowires on gallium nitride layers. CrystEngComm, 22(7), 1239-1250.
  Blumberg, C.; Liborius, L.; Ackermann, J.; Tegude, F.-J.; Poloczek, A.; Prost, W. & Weimann, N.
  
• On-chip 3D confocal optical study of an InGaN/GaN microrod LED in the low excitation regime. Journal of Applied Physics, 130(2).
  Meier, Johanna; Kahl, Julius; Avramescu, Adrian; Strassburg, Martin & Bacher, Gerd
  
• Polarity-controlled AlN/Si templates by in situ oxide desorption for variably arrayed MOVPE-GaN nanowires. Journal of Crystal Growth, 566-567, 126162.
  Häuser, Patrick; Blumberg, Christian; Liborius, Lisa; Prost, Werner & Weimann, Nils
  
• Improving the AlN transfer resistance by ex situ annealing for GaN on Silicon nanowire devices, Nanowire Week, Chamonix, April 25-29, 2022.
  P. Häuser, C. Blumberg, J. Koch, T. Hannappel, N. Weimann & W. Prost
  
• On-chip 3D confocal optical study of an InGaN/GaN microrod LEDs, SPIE Photonics West, San Francisco, USA, January 22 – 27, 2022.
  J. Meier, J. Kahl, A. Avramescu, M. Strassburg & G. Bacher
  
• Progress and Challenges of InGaN/GaN-Based Core–Shell Microrod LEDs. Materials, 15(5), 1626.
  Meier, Johanna & Bacher, Gerd
  
• TEM Analysis of the Si(111)- AlN-GaN Nanowire Interface grown by Polarity- and Site-Controlled Growth, International Workshop on Nitrides, Berlin, Oct. 10-14, 2022.
  P. Häuser, C. Blumberg, W. Prost, M. Bartsch, A. Lorke & N. Weimann
  
• Local optical analysis of InGaN/GaN nanorod LED structures grown on Si(111). Journal of Applied Physics, 134(4).
  Meier, Johanna; Häuser, Patrick; Blumberg, Christian; Smola, Tim; Prost, Werner; Weimann, Nils & Bacher, Gerd