Plasma physics and high-power electronics division
Diamond Electronics Laboratory
The results of the first phase of the project:
A reactor to produce delta layer of boron-doped CVD diamond is designed, it will provide the epitaxial growth of both single-crystal diamond layers of electronic quality (low level of impurities) and controlled growth of delta layers doped with boron.
Publications on the project:
S.A. Bogdanov, A.L. Vikharev, A.M. Gorbachev, A.B. Muchnikov, D.B. Radishev, N.M. Ovechkin and V.V. Parshin, Growth rate enhancement of high quality low-loss CVD diamond disks grown for microwave windows application, Chemical Vapour Deposition, Volume 20, Issue 1-2-3, pages 32–38, March 2014, http://dx.doi.org/10.1002/cvde.201307058
The results of the second phase of the project:
A microwave plasma CVD reactor for growing layers of boron delta-doped CVD diamond was built and tested. A separate microwave plasma CVD reactor operating at 2.45 GHz was used for the epitaxial deposition of single crystal CVD diamond of high quality with nitrogen content in the sample of less than 100 ppb. Such level of nitrogen impurity corresponds to the electronic grade diamond.
Uniformly boron doped CVD diamond layers with a thickness of 2-2.5 um were also grown. The concentration of boron in the grown diamond samples was in the range 1018ыгз> -1020 cm-3. A method for monitoring the level of doping during the growth process of CVD diamond using optical emission spectroscopy of the discharge was developed.
Methods of mechanical polishing of a single crystal HPHT diamond substrates for subsequent diamond homoepitaxial growth of CVD diamond was developed and tested. A series of substrates of (100) oriented HPHT diamond with size of (3,5x3,5x0,5 mm3), with roughness of less than 2? and misorientation angle of not more than 0,1o were prepared. An ICP-RIE etching process of single crystal substrates in an Ar/Cl2 plasma at low pressure (dry etching in an inductively coupled plasma combined with reactive ion etching) for removal of the surface layer of single-crystal diamond substrate damaged during polishing was studied in detail. Etching process of (100) diamond substrates was investigated.
The technology for growing of large-area composite CVD wafers (diameter up to 76 mm) containing more than 100 single-crystal CVD diamonds grown into polycrystalline diamond base was developed. The technology developed includes a junction of poly- and monocrystalline areas during the process of the CVD growth, the removal of mechanical stresses between areas by high-temperature annealing, and the growth of boron-doped epitaxial CVD layers on single-crystal areas of composite wafer. An application of this technology allows one to obtain a combined wafer suitable for creation of electronic devices based on semiconductor CVD diamond using existing manufacturing lines.
New design of a delta-doped conductive channel field-effect transistor based on the use of the new profile of boron concentration distribution in the channel having two closely placed (at a distance of about 3 nm) peaks was proposed and justified by calculations. It was shown that such a doping profile provides increase of mobility and hence increase of channel conductivity by 60% compared with a profile with a single peak.
The simulation of the field effect transistor in which the conducting channel is created using the hydrogen-rich surface layer was made. At the value of the surface charge of 1013 cm-2, the following characteristics of the transistor was obtained: slope of 250 mSim/mm, cut-off frequency 25-30 GHz, frequency of maximum power gain 90-100GHz. It was shown that the voltages and currents in the proposed variant of the transistor is almost an order of magnitude higher than the operating voltages and currents of HEMT transistor with the same geometry.
The simulation of a m-i-p structure Schottky diode was made. The technology of manufacturing of Schottky diodes on the base of semiconductor CVD diamond using the Pt contacts deposited by photolithography was developed. Experimental samples of Schottky diodes using the boron-doped layers of CVD diamond were manufactured and their current-voltage characteristics were examined. The current-voltage and capacitance-voltage characteristics of obtained structures were studied. It was shown that the capacitance-voltage measurements of semiconductor CVD diamond is characterized by a significant deviation from the principle of quasi-static measurement (independence on the test signal frequency). Basing on results of the capacitance-voltage measurements the concentration of main charge carriers (holes) at different temperatures was estimated.
Publications on the project:
A.B. Muchnikov, A.L. Vikharev, D.B. Radishev, V.A. Isaev, O.A. Ivanov, A.M. Gorbachev, A wafer of combined single-crystalline and polycrystalline CVD diamond, Materials Letters, 2015, 139, pp.1-3; http://dx.doi.org/10.1016/j.matlet.2014.10.022
Kukushkin V.A., Snider G.L., Bogdanov S.A., Chernov V.V., Delta layer doping profile in diamond providing high carrier mobility, physica status solidi RRL, Volume 8, Issue 10, pp 876-879, http://dx.doi.org/10.1002/pssr.201409302
Кукушкин В. А., Увеличение радиационного времени жизни экситонов Ванье−Мотта в полупроводниковых нанокластерах, Физика и техника полупроводников, Tом 49, вып.1, http://journals.ioffe.ru/ftp/2015/01/p76-81.pdf
S.P. Antipov, S.V. Baryshev, J.E. Butler, C. Jing, A.D. Kanareykin, P. Schoessow, M. Conde, W. Gai, J.G. Power, S. Stoupin, RF breakdown test of diamond-loaded resonator for high gradient wakefield accelerator applications, Diamond & Related Materials, http://dx.doi.org/10.1016/j.diamond.2014.10.013
Bogatskiy A., James E. Butler, A Geometric Model of Growth for Cubic Crystals: Diamond, Diamond and Related Materials, 53 (2015), 58-65, http://dx.doi.org/10.1016/j.diamond.2014.12.010
Vikharev A.L., Muchnikov A.B., Radishev D,B., Isaev V.A., Ivanov O.A., Gorbachev A.M., Growth and characterization of combined single-crystalline and polycrystalline CVD diamond wafer, MRS Online Proceedings Library, 2014, v.1734, mrsf14-1734-r09-01, http://dx.doi.org/10.1557/opl.2015.41
Ivanov O.A., Muchnikov A.B., Chernov V.V., Bogdanov S.A., Vikharev A.L., Butler J.E., Experimental study of hydrogen plasma etching of (100) single crystal diamond in a MPACVD reactor, Material Letters, http://dx.doi.org/10.1016/j.matlet.2015.03.073
The results of the third phase of the project:
Uniformly boron doped CVD diamond layer with a thickness of 2-2.5 um were produced, the concentration of boron was in the range 1018-1019 cm-3. It was shown that the control of the hydrogen flow through a solution of trimethylborate in ethanol, and adjusting the concentration of trimethylborate allows extending the range of boron doping level of diamond to 1016 to 1021 cm-3. Electrophysical characteristics of boron-doped CVD diamond layer have been investigated by X-ray topography and diffractometry, FT-IR spectroscopy, cathodoluminescence.
As a result of the measurement with a method of admittance spectroscopy the IV and CV characteristics of experimental samples of highly boron-doped diamond single-crystal layers were determined. The dependence of the activation energy of the boron impurities on the degree of doping was determined. A transition to the hopping conductivity type at high concentrations of boron was found.
The ICP-RIE etching process of single crystal substrates in Ar/Cl2 plasma at low pressure was studied in detail. It was shown that the ICP-RIE method is promising for homogeneous (over the entire area of the sample) removal of the surface layer of single-crystal diamond substrate which was damaged in the process of polishing. It was found that the method of etching does not deteriorate the surface roughness achieved during mechanical polishing. It is shown that during the epitaxial growth of single crystal CVD diamond on HPHT substrates structural defects may occur, which are induced by the process of grinding and/or polishing, but not with the characteristics of the deposition regime and/or presence of dislocations in the substrate. It was found that with the etching of substrates in the ICP-RIE plasma, the increase of the etching depth decreases the density of grinding defects up to their complete disappearance.
Homoepitaxial CVD diamond single crystal layers of high quality were grown. Single crystal diamond layers were obtained with a thickness of about 1 mm and higher quality than that of the HPHT diamond substrate.
A setup for study of the diamond by method of "micro-Raman" spectroscopy was made. The apparatus allows measuring Raman and photoluminescence spectra with high spatial resolution (spot size about 1 micron), and provides information about the crystalline perfection of the diamond phase (the width of the peak corresponding to the diamond), and the presence of non-diamond phases (graphite, amorphous carbon), defects and impurities, such as (NV)0, (NV)- and "silicon-vacancy" (Si-V) complexes.
An experimental set of samples with epitaxial layers of CVD diamond were studied by micro-Raman spectroscopy. It was found that the full width at half maximum of the Raman peak corresponding to the diamond is about 1.7 cm-1 on the entire surface of the sample, which indicates a high crystalline perfection of the samples. Measurements showed that the nitrogen content in the samples is only a few ppb.
A fundamentally new type of reactor for growth of boron-doped delta layer CVD diamond was created. For this reactor a special system for supplying gas was developed, providing simultaneous feeding of a gas mixture consisting of six different gases to the reactor and fast switching to another composition of the gas mixture, and having laminar flow of gases in the reaction chamber. Highly boron doped diamond delta-layers with thickness of 2-3 nm were produced in this reactor.
The design and modeling of different devices based on diamond was performed. Modeling of insulated gate p-i-p transistor at different thicknesses of heavily doped layer (200 nm and 50 nm) showed the possibility of obtaining the following characteristics of the device: characteristic slope of about 150-200mSim/mm, cut-off frequency of 20 GHz, frequency of maximum power gain of 80 GHz. This transistor, when compared to a HEMT transistor with the close geometrical sizes, features an order of magnitude higher voltages and currents.
The technology of micro-profiling of diamond substrate by RIPT (reactive ion plasma etching) was developed. It was shown that the method of forming the metal masks allows obtaining high selectivity of the diamond etching. Test mesa-structures with vertical walls and low defects were obtained.
Studies were made on developing the technology of applying Pt – as a metal, that the Pt-diamond structure forms a Schottky barrier with a highest value compared with the technologically available metals, such as: Ni, Ta, W, Ti, Al, V. Platinum was deposited by sputtering on the substrate without the epitaxial layers. It was shown that this technology allows forming a contact of Pt-C with necessary topology by lift-off method and ensures good adhesion of metal to the diamond.
A method for surface passivation of device structures using Al2O3 deposition was proposed to reduce surface leakage current in planar Schottky diodes. The technology of applying the protective insulating layer of Al2O3 (70 nm thick) by atomic layer deposition was developed. The study of obtained Al2O33 films by ellipsometry and electron microscopy showed their high quality and uniformity of deposition.
Contactless method for non-destructive measurements of the microwave characteristics of experimental samples of devices fabricated using delta-doped diamond layers was designed. The basis of this method is the measurement of S-parameters of developed measuring cell and the subsequent calculation of complex permittivity and permeability of the structure in accordance with Nicholson-Ross algorithm. Due to the close relation between the complex permittivity and conductivity of the delta-doped layer, concentration of charge carriers collected in the delta layer is estimated. The simulation of three different designs of the measuring cell was made, optimum cell design based on symmetric microstrip transmission line was selected and produced.
Publications on the project:
M.A. Lobaev, S.A. Bogdanov, D.B. Radishev, A.L. Vikharev, A.M. Gorbachev, Method of power density determination in microwave discharge, sustained in hydrogen-methane gas mixture, Diamond & Related Materials 66 (2016) 177-182, http://dx.doi.org/10.1016/j.diamond.2016.05.004
A.B. Muchnikov, D.B. Radishev, A.L. Vikharev, A.M. Gorbachev, A.V. Mitenkin, M.N. Drozdov, Yu.N. Drozdov, P.A. Yunin, Characterization of interfaces in mosaic CVD diamond crystal, Journal of Crystal Growth, 442 (2016) 62–67, http://dx.doi.org/10.1016/j.jcrysgro.2016.02.026
A. L. Vikharev, A. M. Gorbachev, M. A. Lobaev, A. B. Muchnikov, D. B. Radishev, V. A. Isaev, V. V. Chernov, S. A. Bogdanov, M. N. Drozdov, and J. E. Butler, Novel microwave plasma-assisted CVD reactor for diamond delta doping, Phys. Status Solidi RRL, 1–4 (2016), http://dx.doi.org/10.1002/pssr.201510453
V.A. Kukushkin, S.A. Bogdanov, Simulation of CVD diamond-based high speed near-infrared photodetectors, Diamond & Related Materials 60 (2015) 94–98, http://dx.doi.org/10.1016/j.diamond.2015.10.017
V. I. Zubkov, O. V. Kucherova, S. A. Bogdanov, A. V. Zubkova, J. E. Butler, V. A. Ilyin, A. V. Afanas'ev, A. L. Vikharev, Temperature admittance spectroscopy of boron doped chemical vapor deposition diamond, Journal of Applied Physics 118, 145703 (2015); http://dx.doi.org/10.1063/1.4932664
O. A. Ivanov, A. M. Gorbachev, A. L. Vikharev, M. A. Lobaev, V. A. Isaev, V. V. Chernov, Electron emission amplification of cold cathode by two-layer diamond coating, Phys. Status Solidi A, 212: 1779–1784. http://dx.doi.org/10.1002/pssa.201431799
O.A.Ivanov, A.B.Muchnikov, V.V.Chernov, S.A.Bogdanov, A.L.Vikharev, J.E.Butler, Experimental study of hydrogen plasma etching of (100) single crystal diamond in a MPACVD reactor, Materials Letters, 151 (2015) 115–118, http://dx.doi.org/10.1016/j.matlet.2015.03.073
A. B. Muchnikov, A. L. Vikharev, J. E. Butler, V. V. Chernov, V.A. Isaev, S.A. Bogdanov, A. I. Okhapkin, P. A. Yunin, and Y. N. Drozdov, Homoepitaxial growth of CVD diamond after ICP pretreatment, Phys. Status Solidi A, 212: 2572–2577. http://dx.doi.org/10.1002/pssa.201532171
О.И. Хрыкин, Ю.Н. Дроздов, М.Н. Дроздов, П.А. Юнин, В.И. Шашкин, С.А. Богданов, А.Б. Мучников, А.Л. Вихарев, Д.Б. Радищев, Монокристаллические слои GaN/AlN на CVD-алмазе, Письма в ЖТФ, 2015, том 41, вып. 19, c.8-15
М.А. Лобаев, О.А. Иванов, А.Л Вихарев, А.М. Горбачев, В.А. Исаев, Исследование взаимодействия пучка электронов с сильным высокочастотным полем в волноводном переключателе мощного СВЧ компрессора, Изв. Вузов. Радиофизика, т.58, №.11, c.913-922, (2015)
A.L.Vikharev, A.B.Muchnikov, D.B.Radishev, V.A.Isaev, O.A.Ivanov, A.M. Gorbachev, Growth and characterization of combined single-crystalline and polycrystalline CVD diamond wafer, Pittsburgh, PA, MRS Proceedings, V.1734, (2015), http://dx.doi.org/10.1557/opl.2015.41
Диагностика эффективности возбуждения поверхностных плазмон-поляритонов квантовыми точками с помощью поляризационных измерений выходного излучения, Кукушкин В.А., Физика и техника полупроводников, 2015, том 49, вып 6
O.A. Ivanov, A.L. Vikharev, A.M. Gorbachev, Experimental study of plasma decay in pulsed microwave discharges of H2, CH4 and their mixtures, Plasma sources, science and technology, v.25, N3, 2016
M.A. Lobaev, S.A. Bogdanov, D.B. Radishev, A.L. Vikharev, A.M. Gorbachev, Investigation of microwave discharge in cavity reactor excited in the TM013 mode, Proceedings of IX International workshop “Microwave discharges: fundamentals and applications”, September 7-11, 2015, Cordoba (Spain), pp.83-88
Зубков Василий Иванович, Панов Михаил Федорович, Афанасьев Алексей Валентинович, Ильин Владимир Алексеевич, Ламкин Иван Анатольевич, Батлер Джеймс Эхрич, Вихарев Анатолий Леонтьевич, Богданов Сергей Александрович, На пути к дельта-легированному полупроводниковому алмазу, Нано- и микросистемная техника, 2015, Декабрь, № 12 (185)
Витько Виталий Валерьевич, Кондрашов Александр Викторович, Никитин Андрей Александрович, Батлер Джеймс Эхрич, Измерительная ячейка для исследования СВЧ-свойств дельта-легированных алмазных образцов, Известия вузов России: Радиоэлектроника, 2015, 3
Вихарев А.Л., Лучинин В.В., CVD алмаз – материал для нового поколения электронных приборов: выращивание, характеристики и некоторые применения, Электроника и микроэлектроника СВЧ, 2015. Т. 1. № 1. С. 29-33.
С.А. Богданов, А.Л. Вихарев, М.Н. Дроздов, Исследование синтеза полупроводникового CVD алмаза при высокой степени легирования, Электроника и микроэлектроника СВЧ, 2016. Т. 1. № 1. С. 79-81.
The results of the 4th phase of the project:
The following results were obtained during the implementation of the fourth stage of project.
Publications on the project:
O.A.Ivanov, A.L.Vikharev and A.M.Gorbachev, Experimental study of plasma decay in pulsed microwave discharges of H2, CH4 and their mixtures. Plasma Sources Sci. Technol., 25 (2016) 035017, http://dx.doi.org/10.1088/0963-0252/25/3/035017
A.B.Muchnikov, D.B.Radishev, A.L.Vikharev, A.M.Gorbachev, A.V.Mitenkin, M.lN.Drozdov, Y.N.Drozdov, P.A.Yunin, Characterization of interfaces in mosaic CVD diamond crystal, Journal of Crystal Growth, 442 (2016) 62–67, http://dx.doi.org/10.1016/j.jcrysgro.2016.02.026
V.A. Kukushkin, Simulation of a perfect CVD diamond Schottky diode steep forward current–voltage characteristic, Physica B 498 (2016) 1–6, http://dx.doi.org/10.1016/j.physb.2016.06.011
A.V.Golubkov, A.S.Ivanov, V.A.Ilyin, V.V.Luchinin, S.A.Bogdanov, V.V.Chernov and A.L.Vikharev, Stabilizing effect of diamond thin film on nanostructured silicon carbide field emission array, Journal of Vacuum Science & Technology B 34, 062202 (2016), http://dx.doi.org/10.1116/1.4965727
V.V. Chernov, A.M. Gorbachev, A.L. Vikharev, and M.A. Lobaev, Criterion for comparison of MPACVD reactors working at different microwave frequencies and diamond growth conditions, Phys. Status Solidi A, vol. 213, Issue 10, 2016, pp. 2564–2569, http://dx.doi.org/10.1002/pssa.201600193
A. Tumarkin, S. Razumov, A. Gagarin, A. Altynnikov, A. Mikhailov, R. Platonov, I. Kotelnikov, A. Kozyrev, J. E. Butler, Ferroelectric Varactor on Diamond for Elevated Power Microwave Applications, IEEE Electron Device Letters, V.37, N.6, p. 762-765, June 2016, http://dx.doi.org/10.1109/LED.2016.2554882
J.E. Butler, A. Vikharev, A. Gorbachev, M. Lobaev, A. Muchnikov, D. Radischev, V. Isaev, V. Chernov, S. Bogdanov, M.l Drozdov, E. Demidov, E. Surovegina, V. Shashkin, A. Davidov, H. Tan, L. Meshi, A. C. Pakpour-Tabrizi, M.-L. Hicks, R. B. Jackman, Nanometric diamond delta doping with boron, Phys. Status Solidi RRL, 1–6 (2016), http://dx.doi.org/10.1002/pssr.201600329
Е.А. Суровегина, Е.В. Демидов, М.Н. Дроздов, А.В. Мурель, О.И. Хрыкин, В.И. Шашкин, М.А. Лобаев, А.М. Горбачев, А.Л. Вихарев, С.А. Богданов, В.А. Исаев, А.Б. Мучников, В.В. Чернов, Д.Б. Радищев, Д.Е. Батлер, Атомный состав и электрофизические характеристики эпитаксиальных слоев CVD алмаза, легированных бором, Физика и техника полупроводников, 2016, том 50, вып. 12, стр. 1595-1598
The results of the 5th phase of the project:
1. Studies of homoepitaxial growth of high purity single crystal CVD diamond with a low level of nitrogen impurity of less than 1 ppb have been carried out. A technique for measuring the nitrogen content in a working gas mixture during the deposition of a CVD diamond based on measuring the emission intensity of CN molecule was proposed and tested. Optimum parameters of the reactor operation for obtaining single crystals with low defect density were determined, with the diamond growth rate of 10-15 μm/h. Growth of single-crystal CVD diamond under conditions of extremely high specific energy inputs (more than 1 kW/cm3) were studied. As a result, the epitaxial growth rate of single crystal diamond has reached more than 100 μm/hr.
Publications on the project:
M.A. Lobaev, A.M. Gorbachev, A.L. Vikharev, D.B. Radishev, V.A. Isaev, S.A. Bogdanov, P.A. Yunin, M.N. Drozdov, J.E. Butler, Dependence of boron incorporation in delta layers on CVD diamond growth process and misorientation angle, EPJ Web of Conferences 149, 02014 (2017), 2 pages, http://doi.org/10.1051/epjconf/201714902014
A.L. Vikharev, A.M. Gorbachev, M.A. Lobaev, D.B. Radishev, V.A. Isaev, S.A. Bogdanov, M.N. Drozdov, E.V. Demidov, E.A. Surovegina, V.I. Shashkin, P.A. Yunin, J.E. Butler, CVD diamond with boron-doped delta-layers deposited by microwave plasma, EPJ Web of Conferences 149, 01010 (2017), 2 pages, https://doi.org/10.1051/epjconf/201714901010
J.E. Butler, A.L. Vikharev, A.M. Gorbachev, M.A. Lobaev, A.B. Muchnikov, D.B. Radischev, V.A. Isaev, V.V. Chernov, S.A. Bogdanov, M.N. Drozdov, E.V. Demidov, E.A. Surovegina, V.I. Shashkin, A. Davidov, H.Tan, L. Meshi, A.C. Pakpour-Tabrizi, M.L. Hicks, R.B. Jackman, “Nanometric Diamond Delta Doping with Boron” // Phys. Status Solidi RRL. 2017. 11(1). 1–6. DOI 10.1002/pssr.201600329
M.A. Lobaev, A.M. Gorbachev, A.L. Vikharev, V.A. Isaev, D.B. Radishev, S.A. Bogdanov, M.N. Drozdov, P.A. Yunin, and J.E. Butler. Investigation of boron incorporation in delta doped diamond layers by secondary ion mass spectrometry, Thin Solid Films, Volume 653, May 2018, Pages 215-222, https://doi.org/10.1016/j.tsf.2017.12.008