Materials Science in Semiconductor Processing 107 (2020) 104816 Available online 9 November 2019 1369-8001/© 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Metalorganic vapour-phase epitaxy of AlGaN/GaN heterostructures on chlorine plasma etched GaN templates without buried conductive layer Mateusz Wo� sko a, * , Bogdan Paszkiewicz a , Andrzej Stafniak a , Joanna Pra _ zmowska-Czajka a , Andrej Vincze b , Kornelia Indykiewicz a , Michał Stępniak a , Bartosz Kaczmarczyk a , Regina Paszkiewicz a a Faculty of Microsystem Electronics and Photonic, Wroclaw University of Science and Technology, Janiszewskiego 11/17, 50-372, Wroclaw, Poland b International Laser Center, Ilkovicova 3, 841 04, Bratislava, Slovak Republic A R T I C L E INFO Keywords: Metalorganic vapour phase epitaxy Nitrides RIE Regrowth HEMT Vertical device ABSTRACT In this work we present approach that allows regrowth of AlGaN/GaN heterostructures on plasma etched GaN templates without occurrence of buried conductive layer. Discussion about the infuence of RIE (reactive ion etching) process on the properties of GaN surface is followed by presentation of experimental work results focused on reconstruction of GaN template surface after etching in chlorine plasma in order to growth AlGaN/ GaN heterostructure without parasitic channel. Analysis of GaN surface treatment after RIE process using 10% aqueus HF solution and low temperature GaN (LT-GaN) nucleation layer is carried out, including SEM (scanning electron microscopy) imaging and SIMS (secondary ion mass spectroscopy) profling. The AlGaN/GaN hetero- structures with the thickness as low as 250 nm deposited on plasma etched GaN templates with sheet resistance under 600 Ω/□ and good uniformity were fabricated using this approach. Presented method can be used in fabrication of current aperture vertical electron transistor (CAVET) structures with low leakage currents. 1. Motivation Fabrication of modern microelectronic devices, requires multistage epitaxy [1–5]. One example of such advanced devices is current aperture vertical electron transistor (CAVET) [6–10]. Typically, in the case of CAVET structures, growth of AIII-N materials is realized on substrates spatially structured in various plasma processes, including reactive ion etching. Epitaxial growth on GaN surface, etched by those techniques, becomes diffcult due to surface deterioration after plasma treatment. AlGaN/GaN heterostructures grown directly on etched GaN show presence of unintentionally doped conductive layer located on the etched interface, with donor concentration higher than 10 17 cm -3 , that causes the GaN buffer resistivity degradation. Chlorine based RIE is used to decrease ohmic contact resistivity to n-GaN [11,12] and to reduce carrier concentration in p-GaN [13–15], however presence of parasitic conductive channel in regrown GaN buffer hinder the application of AlGaN/GaN heterostructures for HEMTs (high electron mobility tran- sistors). The origin of donors in GaN after Cl-plasma etching are prob- ably nitrogen vacancies [16] and chlorine complexes [17] on the GaN surface. This parasitic phenomenon is responsible for leakage currents observed in CAVET structures [6,9,10]. In our work we focus on effective method, that could suppress the formation of buried conductive layer in AlGaN/GaN heterostructures grown on Cl plasma etched GaN templates. In our approach, application of low temperature GaN nucleation layer on the etched GaN surface preceded by the 10% aqueus HF solution treatment, gives smooth AlGaN/GaN heterostructure surface without electron accumulation at GaN/GaN interface. The detailed description of experimental scheme will be followed by presentation of characterisation results of examined AlGaN/GaN heterostructures. In particular, the role of etched GaN treatment in 10% HF solution in proper nucleation of subsequent epi- layers will be explained. Moreover, based on SIMS and C-V profling, the infuence of plasma treatment on incorporation of donor-like impu- rities/defects in GaN will be discussed. Finally, the positive infuence of low temperature GaN layer in prohibiting the formation of parasitic conductive layer effect will be shown and explained. * Corresponding author. E-mail address: mateusz.wosko@pwr.edu.pl (M. Wo� sko). Contents lists available at ScienceDirect Materials Science in Semiconductor Processing journal homepage: http://www.elsevier.com/locate/mssp https://doi.org/10.1016/j.mssp.2019.104816 Received 9 July 2019; Received in revised form 27 October 2019; Accepted 30 October 2019