V.E. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine
National Academy of Sciences of Ukraine

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Department for Development and Fluctuation Analysis of Semiconductor Materials and Structures

 pekar  

 

  Grygoriy S. Pekar
  Head of the Department,
  Doctor of Phys. & Math.Sci., Professor
  tel./fax +38 (044) 525-6191,
  e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

 

 

Staff

singaevskiy  Alexander F. Singayevsky
Deputy Head of the Department,
Senior Researcher, Candidate of Phys. & Math.Sci.   
tel. +38 (044) 525-6191
papusha  Vasily P. Papusha
Senior Researcher, Candidate of Technical Sci.    
tel. +38 (044) 525-6191
lokshin
 

Mikhail M. Lokshin
Senior Researcher, Candidate of Phys. & Math.Sci.    
tel. +38 (044)  525-3337
garbar  Nikolay P. Garbar
Senior Researcher, Candidate of Phys. & Math.Sci.    
tel. +38 (044)  525-6453
kudina  Valeria N. Kudina
Researcher, Candidate of Phys. & Math.Sci.    
tel. +38 (044) 525-6453
osipionok  Nicholay M. Osipenok
Researcher
tel.in. 4-93
verivskiy  Іgor N. Verovsky
Researcher
tel.in. 7-05


bondar  Alexey V. Bondar
Leading Engineer
tel.in. 4-85
gerasimenko  Nadezhda V. Gerasimenko
Leading Engineer
tel. +38 (044) 525-6191
stepanenko  Vladimir G. Stepanenko
Leading Engineer
tel.in. 7-05
010pikovets2  Andrey V. Pikovets
Leading Engineer
tel.in. 7-05
majarskiy  Yuri V. Mazharsky
Leading Engineer
tel.in. 7-05
kasinski2  Еugеnу І. Каsinskу
Engineer of the 1st category
tel.in. 7-05
matveychuk Anatoly V. Matveichuk
Technician of the 1st category
tel.in. 4-85

Research

    Department No. 34 was created in 1997 on the basis of two structural laboratories of the institute. The department employs 16 staff, of which one doctor of physical and mathematical sciences, and 5 candidates - senior researchers.
    The main directions of scientific and technical activities of the department are physical and technical studies of semiconductor materials, including physical justification and development of technological methods for producing large crystals and layers of elementary semiconductors and semiconductor compounds (germanium and II-VI compounds), whose parameters satisfy the latest requirements of modern world technology, as well as experimental and theoretical studies of the physical mechanisms of fluctuation processes in semiconductor materials and devices, including the latest ultrasubmicronic semiconductor devices and structures with nanometer-sized elements, and fluctuation diagnostics of semiconductor materials and devices.

Achievement

1. Basic scientific and technical results in the field of physical and technological research of semiconductor materials and devices

 

        1.1. The results of studies of the optical germanium


    Physically justified, patented and developed a new optical material of infrared technique - germanium doped with sodium (previously the volume germanium doping with sodium was considered to be impossible). The developed material is characterized by low values of the optical absorption and scattering in the infrared spectral range, a high degree of homogeneity of the optical and electrical characteristics as well as of the refractive index over the crystal volume.
       Created full scientific-technological line for physical and technological research and mass production of germanium crystals of various shapes and sizes with output up to 500 kg per year, as well as for production of germanium elements for infrared optics (see "Development").

 

1.2.    The results of research of II-VI compounds and their solid solutions


        1.2.1. A new method for high-temperature research of carrier concentration in a crystal under controlled vapor pressure of one of the chemical component of the crystal has been developed. By applying this technique, the mechanisms of defects formation in crystals of cadmium chalcogenides (for example, CdS) under the real conditions of their growing are established; a model of formation of cadmium associates is developed, their parameters and the impacts on the physical properties of crystals are established.
         1.2.2. Physically justified, developed and patented a range of methods for obtaining and postgrowth thermal processing of large single crystals of wide-gap  II-VI compounds with unique properties, including:
         -  a new method for growing the large crystals doped with various impurities (Li, Na, K, Cu, Au, Ag, Au, In, Ga, Cl, I, Mn, Fe, Ni, Co), including a technique for growing the large heavily-doped CdS:Cl crystals with an unusually high degree of uniformity of the physical characteristics;
      - a new method for growing large homogeneous single crystals of solid solutions consisting of components with very different vapor pressures at the growth temperature  (ZnxCd1-xS и ZnxCd1-xSе); the existence of such crystals allowed for the first time to create the laser cathode-ray tubes (quantoscopes) emitting in the blue spectral range; 
        - a fundamentally new, physically justified method for growing large single crystals of cadmium sulfide and cadmium selenide with uniquely high optical strength for these materials (with the destruction threshold of crystals to optical radiation of 300-800 MW/cm2) and low density of dislocations and inclusions (less than 103 cm-2); on the basis of these crystals, the working elements of powerful lasers excited by an electron beam were created, which had a record on its stability parameters.

Characteristics of the best-known large CdS crystals
and the crystals developed in ISP NASU

Characteristics

of the large crystals

Best known

CdS crystals

CdS crystals

developed in ISP NASU

Dislocation density, cm-2

(2÷8)·104

(5÷10)·102

Density of inclusions,

с m-2

~ 5·103 

(~ 30 microns diameter)

10-100 

  (~ 30 microns diameter)

P ore density,

с m-2

~ 5·102  

(~ 30 microns diameter)

Not observed

Vickers microhardness

kG/mm2

65-66

80-85

Threshold for optical destruction, MW/cm2

5 - 20

300 - 800

 

          1.2.3. The technological procedures are developed for manufacturing some structures required for creation semiconductor devices on their basis, among them the following:
          - new (patented) method for fabricating the diode structures based on low-resistivity ZnS single crystals for producing injection LEDs emitting in the blue region of the spectrum, which are characterized by high efficiency, low operating voltage and stable glow; the physical mechanisms of current passing and the model of electroluminescence excitation in MIS structures on which such LEDs have been created, are established;
          -  method for fabricating the structures for diffusion planar waveguides based on CdS and ZnS single crystals;
          - new (patented) method of printed electronics for fabricating CdS/CdTe heterostructures intended for solar cells production.
    Results of physical and technological research of semiconductor materials and devices are reflected in more than 200 scientific papers, reports and patents for inventions and were included   in    a    series   of    works    for   which    Prof.  G.S.Pekar,  Dr.  A.F.Singaevsky   and Dr. M. M.Lokshin awarded the State Prize of Ukraine in Science and Technology for 2011.


2.    Basic results of research of the physical mechanisms of fluctuation processes in semiconductor materials and devices


       Research in the field of fluctuation phenomena in semiconductor materials and devices, founded in the Department and headed for many decades by Professor N.B.Lukyanchikova, are directed, from one side, to identify specific features of the mechanisms of new physical processes and to establish these mechanisms, which is an important scientific problem, and, on the other hand, to carry out a noise diagnostics of advanced semiconductor technologies and to develop the methods for reducing the noise level in semiconductor devices which represents an actual practical problem. The main results of these studies are as follows:
          2.1. New experimental noise methods are developed that have been successfully used for a detailed study of many materials (Si, Ge, GaAs, InSb, AlGaAs, ZnS, CdS, CdSe) and devices (bipolar (BJT, SiGe HBT) and field-effect (MOSFET, FinFET, SiGe MOSFET, JFET) transistors, including SOI CMOS devices, avalanche (ІMPATT) and light-emitting (LED) diodes, avalanche photodiodes (APD), diode lasers).

 

 Lukyanchikova

Professor
Nataliya Borisovna Lukyanchikova
(1937-2011)

 

        2.2. The consistent patterns are established for fluctuation phenomena accompanying the following physical processes: electron tunneling, single-electron processes, the excess current passing through the potential barrier, the injection of minority carriers in Schottky diodes, impact ionization, photoconductivity, photoluminescence, electroluminescence, degradation processes.

         2.3. A number of new quantum-mechanical effects are revealed, namely:
        - effect of electron gas quantization in the inversion channel of FETs on the Coulomb blockade energy, taking place when so-called RTS-noise generated;
       - the presence of the additional Lorentzian noise components in the noise spectra of most advanced field-effect transistors due to tunneling of electrons from the valence band through ultrathin  (≤ 2,5 nm) gate dielectric at sufficiently high front-gate voltages;
       - the presence of 1/f1.7 noise caused by the tunneling electron exchange with traps associated with the interface between the gate oxide and polysilicon gate, under the two-dimensional surface quantization.
         2.4. New results are obtained concerning the 1/f noise problem:
         -  a new universal relation for 1/f noise is established;
      - a new model of the volume 1/f noise  observed in a wide class of diodes and diode lasers, is developed;
         -  a  new mechanism of surface noise in silicon is proposed.


           2.5. Noise diagnostics of modern semiconductor technologies is conducted, as a result of which:           

          - methods for noise characterization of field-effect transistors (MOSFETs) are developed where the transistors are fabricated by 0.35, 0.18, 0.13, 0.1 μm and 90 and 65 nm technologies, including state-of-the-art technologies of uniaxially and biaxially mechanically strained silicon layer and the so-called "high-k" gate dielectrics, characterized by high values of permittivity, as well as technologies of fin-shaped FETs (FinFETs) fabrication; localization of defects in length and width of MOSFET’s channel, as well as in thickness of the gate dielectric of MOSFETs and FinFETs is established;  a correlation between the 1/f noise level and position of the maximum of nitrogen concentration in thin nitrided gate oxide with respect to the interface Si/SiO2 is found; an influence of HALO implantation on short-channel noise effects is established, etc.;
         - a noise autograph  of 0.5  mµ and  1.0  µm SIMOX MOSFET technologies, due to the peculiarities of the gate and buried Si/SiO2 interfaces, is determined;
        - surface defects of a new type, specific for p-Si layers, the surface of which is covered by an oxide, are revealed, and those defects are shown to be the source of intense generation-recombination noise in MOSFETs;
         - surface traps due to the viscous motion of the oxide under the influence of mechanical stresses are revealed in SiGe/Si bipolar ultra-high-frequency heterotransistors which stresses are due to the selective epitaxial growth of the collector;  the suppression of this effect by implanting BF2 into the built-in field oxide is discovered;
       - the method of increasing the life cycle and emission intensity of green LEDs is developed; this method has been successfully implemented by the manufacturers of such diodes;
          - the impact of technology of the transparent ITO contact application on the properties of the emitter and collector junctions in AlGaAs/GaAs microwave heterophototransistors is established;
        - the methods for reducing the noise level of commercial low-frequency transistors, as well as the methods for the non-destructive control of quality and reliability of a number of semiconductor devices are developed.
     
     The results of noise studies carried out under the Professor N.Lukyanchikova’s guidance have been summarized in three monographs:
     1. N.B.Lukyanchikova, "Fluctuation phenomena in semiconductors and semiconductor devices". Radio and Communication, Moscow, 1990, 295 p. (in Russian);
        2. N. B. Lukyanchikova, “Noise Research in Semiconductor Physics”, Gordon & Breach Science Publishers, London, 1997, 411 p.;
     3. N. B. Lukyanchikova // Chapter 10 (Р.201-233) in the book: “Noise and Fluctuation Control in Electronic Devices”, Ed. A.Balandin, American Scientific Publishers. – 2002. - 390 p.,
 as well as in 250 scientific papers, reports and patents for inventions.             
      The results of studies of noise degradation processes in semiconductor materials and devices have been included in a series of works for which Professor N.B.Lukyanchikova awarded the State Prize of Ukraine in Science and Technology for 1995.

 

Development

     In past years, employees of the Department has a great experience in commercializing their developments: several new technologies for growing crystals of II-VI compounds were introduced at the enterprises of the former Ministry of Electronics Industry of the USSR and, in addition, the crystals of II-VI compounds with desired properties were supplied to various companies and firms in accordance with numerous international projects and contracts, among them - a contract with the famous U.S. "McDonnell Douglas Aerospace" company.
    Over the last decade the Department has developed and implemented at the production facilities of the Institute the full technological and research cycle for manufacturing the developed and patented optical germanium of a new type (sodium-doped germanium Ge:Na) as well as optical elements made from it. The production cycle includes more than 25 manufacturing operations, among them - the chemical reduction of germanium dioxide and  obtaining of metal germanium; zone-refining of metal germanium; germanium doping with sodium; germanium crystal growing from the melt, by using different technological method, as  single crystals or large-block crystals with desired shape and size; diameter sizing of cylindrical germanium ingots; manufacturing of blanks for flat windows and spherical lenses; quantitative control of electrical and optical properties of the crystals. The manufacturing line to a significant extent is based on the original technological methods and techniques.
      A serial experimental production of optical germanium crystals Ge:Na in the shape of cylinders with a diameter up to 250 mm as well as parallelepipeds and plates up to 450 × 160 × 60 mm3 in size is established. As of January 2014, the production capacity is up to 500 kg of germanium and its products per year. The material fabricated meets the highest international standards for optical germanium, and some parameters even exceed these standards.
       The numerous international contracts have been concluded with the companies in the U.S. (the main foreign customer), Austria, Germany, Russia, Latvia, Switzerland, as well as contracts with domestic optical instrument enterprises for the supply of optical germanium crystals with set optical and geometric parameters as well as of optical germanium products for infrared optics, such as lens blanks, protective screens, etc. In the last decade the total volume of supplies exceeded 1.5 tons of crystals and their products totaling over 2 million USD. As of January 2014, the signed contracts for the current year for the supply of optical germanium crystals and products totaling about 10 million Ukrainian hryvnia.
    Now the Department is the only manufacturer of optical germanium in Ukraine and meets the needs of all domestic enterprises in optical instrument.

choh000

Ge:Na crystals with specified shape and dimensions, grown by various technological methods (by Stepanov method, immersed shaper method, modified Bridgman method).

 

plast plast000

Sodium-doped optical germanium plate with an area of 500 sq. cm and above 2 cm thick (left) and a blank for the input window (protective screen)
made of this plate intended for infrared imaging system (right).

 

 

 tank

Produced by V.Malyshev plant (Kharkiv, Ukraine), the tank T-84 "Оплот"  (“Stronghold”) (top photo) , which, according to the conclusion of the publishing association Defense Express Media, was recognized as the best military-technical project of 2013 in Ukraine. Below - the enlarged image of the unit for night sighting and aiming. Arrows shown in both photos indicate the protective screen of the unit, made of Na-doped optical germanium plate producted in the Department No.34 of ISP NASU (see previous photo); the plate is characterized by low values of absorption and scattering of infrared radiation and by a high degree of homogeneity of physical characteristics over the plate volume.

 

lpa000 zonka

Setting up the LPA-1 technological installation
for crystal growing

Zone refining of initial germanium

 

 rm8000

 Alloying of initial germanium ingots on the installation “Redmet-8”

 

 

rm10 000 fre 000
Germanium crystals growing
on the installation "Redmet-10M"
Manufacturing of spherical
lens blanks

 

 shlif 000

Diameter sizing of cylindrical germanium crystals

 

 

 sapfir 000

 Crystals growing on the installation "Sapphire"

 

 slif001

Grinding of large optical germanium plates

 

Equipment

1.    Technological equipment


1.1.    Automated installation LPA-1 for growing crystals with 70-kW induction heater (made in France).
1.2.    Apparatus “Redmet-10M”  for growing crystals with 90-kW resistive heater (made in the USSR).
1.3.    Apparatus “Redmet-8”  for growing crystals with 60-kW resistive heater (made in the USSR).
1.4.    Apparatus “Donetz”  for growing crystals with 90-kW induction heater (made in the USSR).
1.5.    Apparatus “Sapphire”  for growing crystals with 90-kW resistive heater (made in the USSR).
1.6.    High-frequency aperiodic generator (70 kW, 30-70 kHz) (made in France).
1.7.    High-frequency generator (70 kW, 30-70 kHz) (made in England).
1.8.    Installation for germanium zone refining with three work zones.
1.9.    Installation for high-temperature regeneration of technological rigging.
1.10.    Installation for high-temperature annealing of materials in different chemical environments (including chemically aggressive environment).
1.11.     Installation for chemical reduction of germanium dioxide in the hydrogen flow.
1.12.    Three automated furnaces SAPHYMO (made in France).
1.13.    Ultrasonic bath with the 4-kW generator UZG 4-2 and magnetostrictive transducers MI-2000.
1.14.    Machine for precision calibration (diameter sizing) of semiconductor boules (made in Switzerland) with an additional system for germanium waste collection.
1.15.    Machine “Almaz-6”  for cutting semiconductor  ingots  (made in the USSR) with an additional system for germanium waste collection.
1.16.    Sphere grinding machines “SH-150K” and “Almaz-70” for manufacturing lens blanks (diameter up to 150 mm) (made in the USSR) with an additional system for germanium waste collection.
1.17.    Grinding and polishing machine “2-PC-100” (made in the USSR) with an additional system for germanium waste collection.
1.18.    Machine RОХON for diamond cutting semiconductor  crystals (made in Germany).
1.19.     Machine ARMSON-160  for disc cutting of semiconductor  crystals (made in Taiwan).
1.20.    Apparatus for polishing semiconductor plates based on grinding machine for metals 3E-711 (made in the USSR) with an additional system for germanium waste collection.
1.21.    Installations for the resistive-type deposition of thin layers VUP-5 and VUP-72 (made in the USSR).
1.22.    Technological line for preparation and recrystallization of semiconductor layers and structures by printed electronics methods.
1.23.    Technological line for chemical processing of semiconductor materials and structures in different environments at different temperatures for a variety of technological and metrological requirements.
1.24.    Installation for the simultaneous growing of 4 semiconductor crystals from the vapor phase by zone crystallization method at temperatures up to 1220°C.
1.25.    Two muffle furnaces with several temperature zones for thermal processing of semiconductor crystals and structures at temperatures up to 1000°C.
1.26.    Four vacuum and gas-distributing posts, including posts for aggressive chemicals.

 

2.    Measuring equipment


2.1.   Apparatus for measuring the spectral characteristics of semiconductors when excited by an electron beam of fast electrons with an energy of 75 keV and a beam current of 120 μA.
2.2.   Two automatic installations for measurements of the spectral density and the power density of the noise voltage in the range from 1 Hz to 300 kHz, as well as of the current-voltage characteristics of semiconductor materials and structures.
2.3.    Complex for spectral and luminescense studies in the wavelength range from
200 nm to 24 μm, which includes:
      - an universal computing spectral complex KSVU-23M;
      - spectrophotometer SF-46;
      - spectrophotometer IKS-29.
2.4.     Complex for metallographic examination, which includes:
       - metallographic polarization microscopes MIM-8 and MIM-35 with video recording;
       - installation for measuring Vickers microhardness TV-2 with a diamond indenter;
       - profilometer-profiler.
2.5.   Complex for ultrasonic flaw detection UC-10PMS.
2.6.   Optical bench OSC- 2TSL with a set of autocollimators.
2.7.   Automated installation for resistivity measurements of semiconductors.
2.8.   Apparatus for measuring the operating parameters of solar cells.
2.9.   Interferometer Kugler.
2.10. Optical quadrant KO-2-10.
2.11. Laser rangefinder (thickness gauge) LMS-100.
2.12. Two optical goniometers of different types.
2.13. Holographic interference installation UIG-22M with a set of lasers of different power and wavelength of the radiation.

 

Projects

1.    Projects on topics of Presidium of National Academy of Sciences of Ukraine

    2003-2005
Physical phenomena in crystals and low-dimensional structures of II-VI compounds and elemental semiconductors and development of new methods for the preparation of these materials and materials-based devices

    2004-2006
Studies of nucleation and crystallization processes in the preparation of optical germanium crystals of large dimensionbs and non-standard shape for  IR  technique.

    2005-2010
Technological research on the preparation and modification of semiconductor structures based on II-VI compounds, polymers and elemental semiconductors intended for solar cells fabrication.

    2006-2008
Finding ways to improve the performance and to develop the new technologies for the production of II-VI compounds and elemental semiconductors to develop a new element base for nano-, photo-and opto-electronics and sensor technique.

    2006-2010
Nonequilibrium and fluctuation electronic processes in materials and structures of modern micro-, nano- and photoelectronics, physical and technological research of processes of preparing new semiconductor materials for infrared and sensor technique.
 
    2011-2015
Photovoltaic, optical and fluctuation phenomena in light-emitting wide-gap semiconductor compounds, semiconductor structures of  micro- and nanoelectronics and development of technological methods for obtaining elemental semiconductors and wide-gap  semiconductor compounds and structures based on them.полупроводников и широкозонных полупроводниковых соединений и структур на их основе.

    2012-2014
Development of technological methods for obtaining and studying the physical properties of zinc oxide layers as a material for white light sources.

    2012-2016
Development of technology for growing large (up to 20 kg) crystalline plates of new-type optical germanium for modern thermal imaging systems and studying mechanisms of scattering of infrared radiation in the developed material.

2.    Projects by State target scientific and technical programs

    2004-2005
Development of casting-based technology for obtainting germanium crystals for optical elements of thermal sensors.

Development of techniques for quality diagnostics of optical germanium bulk single crystals by the scattering of infrared radiation.

Development of express non-destructive technique for quality diagnostics of semiconductor luminescent materials.

Development of methods for obtaining and control of properties of solid solutions of elementary semiconductors for sensor technique.

    2006-2007
Development of technology for high-purity germanium preparatiob by floating zone melting.

Development of technology for growing shaped crystals.

Preparation and certification of the reference number of single-crystalline samples and implementation of techniques for rapid measurements of integral scattering of radiation in germanium crystals.

Development of methods for non-destructive express diagnostics of transmittance of infrared radiation in germanium crystals.

    2008-2017
Development of technology for growing single crystals of detector germanium for ionizing radiation sensors.

Development and creation of technology for producing metallic germanium of semiconductor purity from the raw materials of different origin for optical elements of IR technique.

Development and creation of a complex for electrooptical diagnostics of surface states in semiconductor materials and structures.

Development and creation of a complex for non-destructive ultrasonic methods for detecting defects and their spatial distribution in large semiconductor crystals.

Publications

2017