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Czelej K, Mansoor M, Sarsil MA, Tas M, Sorkhe YA, Mansoor M, Mansoor M, Derin B, Ergen O, Timur S, Ürgen M. Atomistic Origins of Various Luminescent Centers and n-Type Conductivity in GaN: Exploring the Point Defects Induced by Cr, Mn, and O through an Ab Initio Thermodynamic Approach. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2024; 36:6392-6409. [PMID: 39005534 PMCID: PMC11238542 DOI: 10.1021/acs.chemmater.4c00178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 06/10/2024] [Accepted: 06/11/2024] [Indexed: 07/16/2024]
Abstract
GaN is a technologically indispensable material for various optoelectronic properties, mainly due to the dopant-induced or native atomic-scale point defects that can create single photon emitters, a range of luminescence bands, and n- or p-type conductivities. Among the various dopants, chromium and manganese-induced defects have been of particular interest over the past few years, because some of them contribute to our present-day light-emitting diode (LED) and spintronic technologies. However, the nature of such atomistic centers in Cr and Mn-doped GaN is yet to be understood. A comprehensive defect thermodynamic analysis of Cr- and Mn-induced defects is essential for their engineering in GaN crystals because by mapping out the defect stabilities as a function of crystal growth parameters, we can maximize the concentration of the target point defects. We therefore investigate chromium and manganese-induced defects in GaN with ab initio methods using the highly accurate exchange-correlation hybrid functionals, and the phase transformations upon excess incorporation of these dopants using the CALPHAD method. We also investigate the impact of oxygen codoping that can be unintentionally incorporated during crystal growth. Our analysis sheds light on the atomistic cause of the unintentional n-type conductivity in GaN, being ON-related. In the case of Cr doping, the formation of CrGa defects is the most dominant, with an E +/0 charge transition at E VBM + 2.19 eV. Increasing nitrogen partial pressure tends to enhance the concentration of CrGa. However, in the case of doping with Mn, several different Mn-related centers can form depending on the growth conditions, with MnGa being the most dominant. MnGa possesses the E 2+/+, E +/0, and E 0/- charge transitions at 0.56, 1.04, and 2.10 eV above the VBM. The incorporation of oxygen tends to cause the formation of the MnGa-VGa center, which explains a series of prior experimental observations in Mn-doped GaN. We provide a powerful tool for point defect engineering in wide band gap binary semiconductors that can be readily used to design optimal crystal growth protocols.
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Affiliation(s)
- Kamil Czelej
- Faculty
of Chemical and Process Engineering, Warsaw
University of Technology, Waryńskiego 1, 00-645 Warsaw, Poland
- Department
of Complex System Modeling, Institute of Theoretical Physics, Faculty
of Physics, University of Warsaw, Ludwika Pasteura 5, 02-093 Warsaw, Poland
| | - Mubashir Mansoor
- Metallurgical
and Materials Engineering Department, Istanbul
Technical University, 34469 Maslak, Istanbul, Turkey
- Department
of Applied Physics, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Mehmet Ali Sarsil
- Department
of Electronics and Communications Engineering, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Mert Tas
- Department
of Electronics and Communications Engineering, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Yahya A. Sorkhe
- Metallurgical
and Materials Engineering Department, Istanbul
Technical University, 34469 Maslak, Istanbul, Turkey
| | - Mehya Mansoor
- Metallurgical
and Materials Engineering Department, Istanbul
Technical University, 34469 Maslak, Istanbul, Turkey
- Department
of Geological Engineering, Istanbul Technical
University, 34469 Maslak, Istanbul, Turkey
| | - Maryam Mansoor
- Metallurgical
and Materials Engineering Department, Istanbul
Technical University, 34469 Maslak, Istanbul, Turkey
- Nuclear
Engineering Department, Energy Institute, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
- Department
of Mining Engineering, Istanbul Technical
University, 34469 Maslak, Istanbul, Turkey
| | - Bora Derin
- Metallurgical
and Materials Engineering Department, Istanbul
Technical University, 34469 Maslak, Istanbul, Turkey
| | - Onur Ergen
- Department
of Electronics and Communications Engineering, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey
| | - Servet Timur
- Metallurgical
and Materials Engineering Department, Istanbul
Technical University, 34469 Maslak, Istanbul, Turkey
| | - Mustafa Ürgen
- Metallurgical
and Materials Engineering Department, Istanbul
Technical University, 34469 Maslak, Istanbul, Turkey
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Sawicka M, Turski H, Sobczak K, Feduniewicz-Żmuda A, Fiuczek N, Gołyga O, Siekacz M, Muziol G, Nowak G, Smalc-Koziorowska J, Skierbiszewski C. Nanostars in Highly Si-Doped GaN. CRYSTAL GROWTH & DESIGN 2023; 23:5093-5101. [PMID: 37426547 PMCID: PMC10326854 DOI: 10.1021/acs.cgd.3c00317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/27/2023] [Indexed: 07/11/2023]
Abstract
Understanding the relation between surface morphology during epitaxy of GaN:Si and its electrical properties is important from both the fundamental and application perspectives. This work evidences the formation of nanostars in highly doped GaN:Si layers with doping level ranging from 5 × 1019 to 1 × 1020 cm-3 grown by plasma-assisted molecular beam epitaxy (PAMBE). Nanostars are 50-nm-wide platelets arranged in six-fold symmetry around the [0001] axis and have different electrical properties from the surrounding layer. Nanostars are formed in highly doped GaN:Si layers due to the enhanced growth rate along the a-direction ⟨112̅0⟩. Then, the hexagonal-shaped growth spirals, typically observed in GaN grown on GaN/sapphire templates, develop distinct arms that extend in the a-direction ⟨112̅0⟩. The nanostar surface morphology is reflected in the inhomogeneity of electrical properties at the nanoscale as evidenced in this work. Complementary techniques such as electrochemical etching (ECE), atomic force microscopy (AFM), and scanning spreading resistance microscopy (SSRM) are used to link the morphology and conductivity variations across the surface. Additionally, transmission electron microscopy (TEM) studies with high spatial resolution composition mapping by energy-dispersive X-ray spectroscopy (EDX) confirmed about 10% lower incorporation of Si in the hillock arms than in the layer. However, the lower Si content in the nanostars cannot solely be responsible for the fact that they are not etched in ECE. The compensation mechanism in the nanostars observed in GaN:Si is discussed to be an additional contribution to the local decrease in conductivity at the nanoscale.
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Affiliation(s)
- Marta Sawicka
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Henryk Turski
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Kamil Sobczak
- Faculty
of Chemistry, Biological, and Chemical Research Center, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Anna Feduniewicz-Żmuda
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Natalia Fiuczek
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Oliwia Gołyga
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Marcin Siekacz
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Grzegorz Muziol
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Grzegorz Nowak
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Julita Smalc-Koziorowska
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
| | - Czesław Skierbiszewski
- Institute
of High Pressure Physics, Polish Academy
of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland
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Spasevski L, Buse B, Edwards PR, Hunter DA, Enslin J, Foronda HM, Wernicke T, Mehnke F, Parbrook PJ, Kneissl M, Martin RW. Quantification of Trace-Level Silicon Doping in Al x Ga 1-xN Films Using Wavelength-Dispersive X-Ray Microanalysis. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:696-704. [PMID: 34218838 DOI: 10.1017/s1431927621000568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Wavelength-dispersive X-ray (WDX) spectroscopy was used to measure silicon atom concentrations in the range 35-100 ppm [corresponding to (3-9) × 1018 cm-3] in doped AlxGa1-xN films using an electron probe microanalyser also equipped with a cathodoluminescence (CL) spectrometer. Doping with Si is the usual way to produce the n-type conducting layers that are critical in GaN- and AlxGa1-xN-based devices such as LEDs and laser diodes. Previously, we have shown excellent agreement for Mg dopant concentrations in p-GaN measured by WDX with values from the more widely used technique of secondary ion mass spectrometry (SIMS). However, a discrepancy between these methods has been reported when quantifying the n-type dopant, silicon. We identify the cause of discrepancy as inherent sample contamination and propose a way to correct this using a calibration relation. This new approach, using a method combining data derived from SIMS measurements on both GaN and AlxGa1-xN samples, provides the means to measure the Si content in these samples with account taken of variations in the ZAF corrections. This method presents a cost-effective and time-saving way to measure the Si doping and can also benefit from simultaneously measuring other signals, such as CL and electron channeling contrast imaging.
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Affiliation(s)
- Lucia Spasevski
- Department of Physics, SUPA, University of Strathclyde, GlasgowG4 0NG, UK
| | - Ben Buse
- School of Earth Sciences, University of Bristol, BristolBS8 1RJ, UK
| | - Paul R Edwards
- Department of Physics, SUPA, University of Strathclyde, GlasgowG4 0NG, UK
| | - Daniel A Hunter
- Department of Physics, SUPA, University of Strathclyde, GlasgowG4 0NG, UK
| | - Johannes Enslin
- Institute of Solid State Physics, Technische Universität Berlin, BerlinD-10623, Germany
| | - Humberto M Foronda
- Institute of Solid State Physics, Technische Universität Berlin, BerlinD-10623, Germany
| | - Tim Wernicke
- Institute of Solid State Physics, Technische Universität Berlin, BerlinD-10623, Germany
| | - Frank Mehnke
- Institute of Solid State Physics, Technische Universität Berlin, BerlinD-10623, Germany
| | - Peter J Parbrook
- Tyndall National Institute, University College Cork, CorkT12 R5CP, Ireland
| | - Michael Kneissl
- Institute of Solid State Physics, Technische Universität Berlin, BerlinD-10623, Germany
- Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, BerlinD-12489, Germany
| | - Robert W Martin
- Department of Physics, SUPA, University of Strathclyde, GlasgowG4 0NG, UK
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Gubal A, Chuchina V, Sorokina A, Solovyev N, Ganeev A. MASS SPECTROMETRY-BASED TECHNIQUES FOR DIRECT QUANTIFICATION OF HIGH IONIZATION ENERGY ELEMENTS IN SOLID MATERIALS-CHALLENGES AND PERSPECTIVES. MASS SPECTROMETRY REVIEWS 2021; 40:359-380. [PMID: 32619078 DOI: 10.1002/mas.21643] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/18/2020] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
The determination of nonmetals, first of all, the most electronegative ones-nitrogen, oxygen, fluorine, chlorine, and bromine, poses the highest challenge for element analysis. These elements are characterized by high reactivity, volatility, high ionization energy, and the absence of intensive spectral lines in the optical spectral range. Conventional techniques of their quantification include considerable "wet chemistry" stages so the application of these techniques for the solid sample is highly laborious and prone to uncontrollable uncertainties. Additionally, current development in material science and other areas requires the quantification of the elements at lower levels with good sensitivity. Owing to their robustness and flexibility, mass spectrometry techniques provide vast possibilities for the quantification, spatial and isotopic analysis, including the solutions for direct analysis of solids. The current review focuses on the application of major mass spectrometric techniques for the quantification of N, O, F, Cl, and Br in solid samples. The following techniques are mainly considered: thermal ionization mass spectrometry (TIMS), isotope-ratio MS (IRMS), secondary ion MS (SIMS), inductively coupled plasma MS (ICP-MS), and glow discharge MS (GDMS); as the most accessible and widely applied for the purpose. General ionization issues, advantages, limitations, and novel methodological solutions are discussed. © 2020 John Wiley & Sons Ltd.
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Affiliation(s)
- Anna Gubal
- Institute of Chemistry, St. Petersburg State University, Universitetskaya nab. 7/9, Saint Petersburg, 199034, Russia
| | - Victoria Chuchina
- Institute of Chemistry, St. Petersburg State University, Universitetskaya nab. 7/9, Saint Petersburg, 199034, Russia
| | - Angelina Sorokina
- Institute of Chemistry, St. Petersburg State University, Universitetskaya nab. 7/9, Saint Petersburg, 199034, Russia
| | - Nikolay Solovyev
- Institute of Chemistry, St. Petersburg State University, Universitetskaya nab. 7/9, Saint Petersburg, 199034, Russia
- Institute of Technology Sligo, Ash Lane, Sligo, F91 YW50, Ireland
| | - Alexander Ganeev
- Institute of Chemistry, St. Petersburg State University, Universitetskaya nab. 7/9, Saint Petersburg, 199034, Russia
- Institute of Toxicology of Federal Medico-Biological Agency, ul. Bekhtereva 1, St. Petersburg, 192019, Russia
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The impact of dislocations on AlGaN/GaN Schottky diodes and on gate failure of high electron mobility transistors. Sci Rep 2020; 10:17252. [PMID: 33057086 PMCID: PMC7560755 DOI: 10.1038/s41598-020-73977-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 09/23/2020] [Indexed: 11/08/2022] Open
Abstract
GaN epitaxially grown on Si is a material for power electronics that intrinsically shows a high density of dislocations. We show by Conductive Atomic Force Microscopy (C-AFM) and Defect Selective Etching that even for materials with similar total dislocation densities substantially different subsets of dislocations with screw component act as current leakage paths within the AlGaN barrier under forward bias. Potential reasons are discussed and it will be directly shown by an innovative experiment that current voltage forward characteristics of AlGaN/GaN Schottky diodes shift to lower absolute voltages when such dislocations are present within the device. A local lowering of the Schottky barrier height around conductive dislocations is identified and impurity segregation is assumed as responsible root cause. While dislocation related leakage current under low reverse bias could not be resolved, breakdown of AlGaN/GaN Schottky diodes under high reverse bias correlates well with observed conductive dislocations as measured by C-AFM. If such dislocations are located near the drain side of the gate edge, failure of the gate in terms of breakdown or formation of percolation paths is observed for AlGaN/GaN high electron mobility transistors.
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