Maya Mikhailova, Anatoly Veinger, Igor Kochman, Petr Semenikhin, Karina V. Kalinina, Robert Parfeniev, Vyacheslav Berezovets, Mikhail Safonchik, Alice Hospodková, Jiří Pangrác, Markéta Zíková, Eduard Hulicius
Strong Shubnikov-de Haas (SdH) oscillations were observed in the derivative of microwave absorption (f=10 GHz) in InAs/GaSb/AlSb composite quantum wells (CQWs) using electron-paramagnetic resonance spectroscopy at low temperatures (2.7 to 20 K) and in the magnetic field up to 14 kOe. CQWs were grown on n-GaSb:Te(100) and n-InAs:Mn(100) substrates with various widths of QWs by MOVPE. A predominant contribution to the bulk n-GaSb substrate in SdH oscillations was manifested. Two frequencies of the SdH oscillations connected with warping of the Fermi surface of GaSb were found from Fourier analysis. An unusual angular indicatrix was observed in dependence on the orientation of the samples grown on n-GaSb in the magnetic field. The obtained results can be explained by bulk inversion asymmetry, which is a feature of substances with a lack of inversion centers. For CQWs grown on n-InAs:Mn substrate, only several SdH oscillations with higher period were observed. We succeeded in extracting a contribution of the two-dimensional carriers of InAs QW∼H⊥, where H⊥=H·cos Θ, from bulk substrate oscillations using a special spline interpolation from the angular dependence of SdH oscillatory amplitudes in the angle range of 0 to 90 deg.
Maya Mikhaliova, Anatoly Veinger, Igor Kochman, Petr Semenikhin, Karina Kalinina, Robert Parfeniev, Vyacheslav Berezovets, Alice Hospodková, Jiří Pangrác, Eduard Hulicius
Strong Shubnikov – de Haas (SdH) oscillations were observed in the derivative of microwave absorption (f = 10 GHz) in the InAs/GaSb/AlSb composite quantum wells (CQWs) using electron-paramagnetic-resonance spectroscopy at low temperatures (2.7–20 K) and in the magnetic field up to 14 kOe. CQWs were grown on the n-GaSb:Te(100) and n- InAs:Mn(100) substrates with various width of QWs by MOVPE. Predominance contribution of the bulk n-GaSb substrate in SdH oscillations was manifested. Two frequencies of the SdH oscillations were found from Fourier analysis, which is connected to warping of the Fermi surface of GaSb. Unusual angular indicatrix was observed in dependence on orientation of the samples in the magnetic field. Obtained results can be explained by inversion asymmetry, which is a feature of the substances with lack of inversion centres. For CQWs grown on n-InAs:Mn (ns = 1.1 × 1017 cm-3) substrate, only several SdH oscillations with higher period were observed. Taking into account isotropic Fermi surface of bulk InAs, we succeeded to extract a contribution of the 2D carriers of InAs QW ~ H⊥,where H⊥= HconstcosΘ, from bulk substrate oscillations using special spline interpolation from angular dependence of SdH oscillatory amplitudes in the angle range 0–90°. 2D electron concentration in the InAs QW ns ≈ 1 – 3 × 1011 cm-2 was evaluated from oscillatory period.
The electroluminescent properties of an n-GaSb/n-InGaAsSb/p-AlGaAsSb heterostructure with a high potential barrier in the conduction band (large conduction-band offset) at the n-GaSb/n-InGaAsSb type-II heterointerface (ΔEc = 0.79 eV) are studied. Two bands with peaks at 0.28 and 0.64 eV at 300 K, associated with radiative recombination in n-InGaAsSb and n-GaSb, respectively, are observed in the electroluminescence spectrum. In the entire temperature range under study, T = 290 – 480 K, additional electron-hole pairs are formed in the n-InGaAsSb active region by impact ionization with hot electrons heated on the large the conduction-band offset. These pairs contribute to radiative recombination, which leads to a nonlinear increase in the electroluminescence intensity and output optical power with increasing pump current. A superlinear increase in the emission power of the long-wavelength band is observed upon heating in the temperature range T = 290 – 345 K, and a linear increase is observed at T < 345 K. Theoretical calculations have shown that this behavior of the temperature dependence of the optical power caused by competition between the radiative recombination, thermionic emission and Auger recombination.
Maya Mikhailova, Edward Ivanov, Leonid Danilov, Andrei Petukhov, Karina Kalinina, Nikolai Stoyanov, Yuri Yakovlev, Alice Hospodková, Jiri Pangrác, Jiri Oswald, Marketa Ziková, Edward Hulicius
We report on superlinear electroluminescent structures based on AlSb/InAs1-xSbx/AlSb deep quantum well grown by
MOVPE on n-GaSb:Te substrate. Dependence of the electroluminescence (EL) spectra and optical power on the drive
current in nanoheterostructures with AlSb/InAs1-xSbx/AlSb quantum well at 77 – 300 K temperature range was studied.
Intensive two-band superlinear EL in the 0.5 - 0.8 eV photon energy range was observed. Optical power enhancement
with the increasing drive current at room temperature is caused by the contribution of the additional electron-hole pairs
due to the impact ionization by the electrons heated at the high band offset between AlSb and the first electron level Ee1
in the InAsSb QW. Study of the EL temperature dependence at 90 – 300 K range enabled us to define the role of the first
and second heavy hole levels in the radiative recombination process. It was shown that with the temperature decrease,
the relation between the energies of the valence band offset and the second heavy hole energy level changes due to the
temperature transformation of the energy band diagram. That is why the EL spectrum revealed radiative transitions from
the first electron level Ee1 to the first hole level Eh1 in the whole temperature range (90 – 300 K) while the emission band
related with the transitions to the second hole level occurred only at T < 200 K.
M. Mikhailova, G. Zegrya, L. Danilov, E. Ivanov, K. Kalinina, N. Stoyanov, Kh. Salikhov, Yu. Yakovlev, E. Hulicius, A. Hospodkova, J. Pangrac, M. Zikova
We report on the observation of superlinear electroluminescence in nanoheterostructures based on GaSb with a deep
narrow Al(As)Sb/InAsSb/Al(As)Sb quantum well in the active region, grown by metal organic vapor phase epitaxy.
Electroluminescence spectra for different driving currents were measured at temperatures of 77 and 300 K. It is shown
that such structure exhibits superlinear dependence of optical power on the drive current and its increase of 2-3 times in the current range 50-200 mA. This occurs due to impact ionization in the Al(As)Sb/InAsSb quantum well in which a
large band offset at the interface ΔEC = 1.27 eV exceeds ionization threshold energy for electrons in the narrow-gap well. Theoretical calculation of the size quantization energy levels is presented, and possible cases of impact ionization, depending on the band offset ΔEC at the interface and on the quantum well width, are considered. This effect can be used to increase quantum efficiency and optical power of light emitting devices (LEDs, lasers) operating in mid-infrared spectral range, as well as for photovoltaic elements.
We report on study of electrical and optical properties of type II heterostructures with InSb quantum dots (QDs) inserter
into the InAs-based p-n junction made by LPE-MOVPE combine method. InSb QDs were grown on an InAs(100)
substrate by LPE. Overgrowth on the surface with the self-assembled InSb QD arrays was performed by MOVPE using
capping layers based on binary InAs and quaternary InAsSb solid solutions. High-resolution cross-sectional image of the
InSb QDs buried into the InAs(Sb,P) matrix was obtained for the first time by transmission electron microscopy.
Structural parameters of the InSb QDs such as size, shape and internal strain were demonstrated and discussed. The
uniform small QDs with high density (>1010 cm-2) with dimensions of 3 nm in height and 14 nm in diameter were found
to be self-assembled and dislocation-free without any extended defects, whereas the low-density large QDs (108 cm-2)
with dimensions of 10 nm in height and 50 nm in diameter were relaxed and demonstrated interface strain with the InAs
substrate. I-V characteristics of the mesa-diode heterostructures with the InSb QDs inserted into InAs p-n junction were
studied at the wide temperature range T=77-300 K. Intense positive and negative electroluminescence for both n-InAs/p-
InAs and n-InAs/InSb-QDs/p-InAs heterostructures was found in the spectral range 3-4 μm. Evolution of the spectra in
dependence on applied external bias (forward and reverse) were observed at 77 K and 300 K.
Low- noise avalanche photodiodes for the spectral range of 1.6-2.4 μm were created using the GaInAsSb solid solution
in the absorption region and the wide-gap GaAlX(As)Sb alloy of resonant composition (x=0.04) in the multiplication
region. This APD has a very high ratio of ionization coefficients, β/α>30 and low excess noise factor, F~1.6 (M=10).
The sensitivity of a receiver for longwavelength communication (λ=1.6-2.5 μm) based on GaInAsSb/AlGa(As)Sb SAM
APD is reported. The sensitivity for a direct detection receiver using the SAM APD was calculated according to the
treatment of Personick at bit rate B=500 Mbit/s. The dependence of minimum detectable power η<PAPD> on
multiplication M for the SAM APD for the wavelength λ=2.1 μm was calculated and compared with one for a standard
Ge APD operating at λ=1.55 μm. A minimum detectable power level η<PAPD> = -42.3 dBm at Mopt=34-39 and
η<PAPD>=-41.8 dBm at Mopt=10 of the receivers with the GaInAsSb/GaAl(As)Sb SAM APD and the Ge APD,
respectively were obtained. These results demonstrate the potential of an optical receiver with the
GaInAsSb/GaAl(As)Sb SAM APD for use in mid-IR wavelength optical communication system as well as of great
interest for their potential applications in laser range-finding system.
We report a study of InSb quantum dots and quantum rings grown on InAs(100) substrate by LPE-MOVPE combine
method. Characterization of InSb/InAs(Sb,P) quantum dots was performed using atomic force microscopy and
transmission electron microscopy. The bimodal growth of uncapped InSb quantum dots was observed in the temperature
range T=420-450 °C. The low-density (5×108 cm-2) large quantum dots with dimensions of 12-14 nm in height and 45-50
nm in diameter are appeared at 445 °C, whereas high-density (1×1010 cm-2) dislocation-free small quantum dots with
dimensions of 3-5 nm in height and 11-13 nm in diameter were obtained at 430 °C. Capping of the InSb quantum dots by
binary InAs or InAsSbP epilayers lattice-matched with InAs substrate was performed using MOVPE method. Tunnel-related
behavior in a forward curve of I-V characteristics was observed in heterostructures with buried InSb quantum
dots inserted in InAs p-n junction. Evolution of electroluminescence spectra on driving current at negative bias and
suppression of negative luminescence from buried InSb/InAs quantum dots were found out in the spectral range 3-4 μm
at 300 K. Deposition from the InSb melt over the InAsSb0.05P0.10 capping layer resulted in the formation of InSb quantum
rings with outer and inner diameters about 20-30 nm and 15-18 nm respectively. Surface density of the quantum rings of
2.6×1010 cm-2 was reached at 430 °C.
Mid-infrared photovoltaic detector (PD) designed on the base of a type II p-InAs/p-GaSb asymmetric heterostructure
with a deep AlSb/InAsSb/AlSb quantum well (QW) at the interface is reported. The heterostructures containing the
single QW were grown by LP-MOVPE. Transport, electroluminescent and photoelectrical properties of these structures
were investigated. Intense both positive and negative electroluminescence was observed in the spectral range 3-4 µm
above room temperature (300-400 K). Spectral response in the mid-infrared range 1.2-3.6 μm was obtained at
temperatures T=77-300 K. High quantum efficiency η=0.6-0.7 responsivity Sλ=1.4-1.7 A/W and detectivity
Dλ* =3.5×1011 cm Hz1/2w-1 were achieved at 77 K. Such QW PDs are suitable for heterodyne spectroscopy and free
space communication using quantum cascade lasers as well as for gas analysis and ecological monitoring applications.
Light-emitting diodes (LEDs) and spectral-matched photodiodes (PDs) based on GaInAsSb/AlGaAsSb and InAs/InAsSbP heterostructures grown by LPE and MOVPE for the spectral range 1.6-4.8 μm are presented. New aproach have been proposed to increase quantum efficiency and optical power of the LEDs. Optical sensors based on the LEDs and PDs are considered for detection of methane, carbon dioxide and some anaesthetics for medicine.
This paper reviews some recent developments in the high-speed photodiodes for 2.0-4.0 im spectral range. We report
investigation, design and fabrication of broad bandwidth (2 GHz) GaInAsSb/GaA1AsSb p-i-n photodiodes operating in
the 0.9-2.4 μm spectral range with submicroampere dark cunent. As well, we present InAs-based and InAs/InAsSbP
photodiodes with long-wavelength cutoff of 3.8 μm. An analysis of the photodiode performance through the
investigation of current-voltage, capacitance-voltage and spectral responsivity characteristics was carried out. Also, noise
and speed-response characteristics were studied. In addition to high-speed response and low noise level these
photodiodes offer room-temperature operation and hence are commercially viable. These devices are of great interest for
a wide range of applications, such as high-resolution laser diode spectroscopy of gases and molecules, eye-safe laser
rangefinding systems, the free-space optical link as well as systems of optical fiber communication.
The observation of the Quantum Hall effect (QHE) in a semimetal channel with coexisting electrons and holes, simultaneously, at the type II broken-gap p-GaIn0.16As0.22Sb/p-InAs single heterointerface based on unintentionally doped quaternary solid solution obtained by liquid phase epitaxy (LPE) was reported for the first time elsewhere. In this report the quantum magnetotransport in the p-Ga0.84In0.16As0.22Sb0.78/p-InAs single heterostructure has been studied for a set of the samples with the both undoped and doped with Zn impurity quaternary layer at low temperatures in high magnetic fields up to 14 T.
We have proposed a new physical approach for the design of mid-IR lasers operating at λ = 3.2 - 3.26 μm based on type II heterojunctions with a large asymmetric band-offset at the interface (ΔEC > 0.6 eV and ΔEV > 0.35 eV). These high potential barriers produce effective electron-hole confinement at the interface and results in a tunnel-injection radiative recombination mechanism within the device due to reduce leakage current from the active region. The creation of high barriers for carriers leads to their strong accumulation in the active region and increases quantum emission efficiency of the spatially separated electrons and holes across the heteroboundary. Our approach also leads to the suppression of non-radiative Auger-recombination and a corresponding increase in the operation temperature of the laser. The active region of the laser structure consists of the type II heterojunction formed by narrow-gap In0.83Ga0.17As0.82Sb0.18 (Eg = 0.393 eV at 77 K) and wide-gap Ga0.84In0.16As0.22Sb0.78 (Eg = 0.635 eV at 77 K) layers lattice-matched to InAs substrate.
We present a novel hybrid laser structure based on III-V and II-VI compounds combining some advantages of type I and type II heterojunctions in one heterostructure. Such design allows the achievement of large energy offsets at the interface in the conduction and the valence band exceeding of 1.0 eV in order to provide good electron and hole confinement. P-AlAsSb/n-InAs/N-Cd(Mg)Se laser heterostructures were grown on p-InAs substrates by original technology of MBE method in two separate growth chambers consequently. Photoluminescence spectra included tow emission bands at hv=0.41 eV and hv=2.08 eV associated with InAs and CdMgSe bulk recombination transitions, respectively. Intense electroluminescence was observed at (lambda) =2.73micrometers (77K) and (lambda) =3.12micrometers (300K). Weak temperature dependence of spontaneous emission indicated the effective carrier confinement in the InAs layer due to large potential barriers ((Delta) sEc=1.28eV and (Delta) EV=1.68eV). Proposed hybrid III-V/II-VI heterostructure is very promising for creation the mid-infrared lasers with improved performances operating in the spectral range of 3- 5micrometers .
In the present paper, we report the results of our investigation, which aims to upgrade the GaInAsSb-based photodiode heterostructure technology. The main requirements on GaInAsSb solid solutions from the viewpoint of near-infrared photodiode applications are considered. Such methods for decreasing a carrier concentration in the epitaxial layers of the solid solutions as doping with a donor impurity, the use of rare-earth element Yb, growth from lead containing melt are discussed. The possibility of decreasing the GaInAsSb band gap resulting in long- wavelength photosensitivity threshold shift is demonstrated. We have made GaInAsSb/GaAlAsSb photodiodes with the long- wavelength photosensitivity threshold of 2.4 micrometers . At -2V reverse bias a lowest dark current density is 3x10-3 A/cm2, and the quantum efficiency is 60-70% at (lambda)=2.0-2.1micrometers .
We have proposed a new physical approach to design mid-IR lasers based on type II heterostructures with strong asymmetric band offset confinement at the interface. It allows to create the high barriers for carriers and to reduce leakage current from an active region, that leads to increase the quantum efficiency of the emission due to the strong accumulation of recombining carriers. Here this approach was successfully used for fabrication high power lasers operating at (lambda) equals 3.26 micrometers . The laser structure containing narrow-gap active InGaAsEb (Eg equals 0.380 eV) layer and wide-gap confined InAsSbP (Eg equals 0.520 eV) and GaInAsSb (Eg equals 0.640 eV) layers lattice-matched to InAs substrate was grown by LPE. Such heterostructure has the band energy diagram with strong asymmetric band offsets and allows to provide high barriers for electrons at the InGaAsSb/GaInAsSb heterointerface ((Delta) Ec equals 0.60 eV) and for holes at the InGaAsSb/InAsSbP one ((Delta) Ev equals 0.15 eV). Maximum output power of 1.5 W was achieved in pulsed mode with pulse duration 1 microsecond(s) and repetition rate 100 Hz for 100 micrometers broad area laser with cavity length about of 1000 micrometers . Threshold current density was about 450 A/cm2. Characteristic temperature T0 equals 47 K was observed in the range of 77 - 140 K.
Comparative study of threshold current temperature dependence, differential quantum efficiency and light polarization was performed for type I and type II InAsSb/InAsSbP heterostructures as well as for tunneling- injection GaInAsSb/InGaAsSb laser based on this type II broken-gap heterojunction. Experimental evidence of non- radiative Auger-recombination suppression in type II InAsSb/InAsSbP heterolasers with high band-offset ratio (Delta) Ev/(Delta) Ec equals 3.4 was obtained. Reduction of temperature dependence of the threshold current was demonstrated for both kinds of type II lasers. Maximum operation temperature and characteristic temperature T equals 203 K with T0 equals 40 K and T equals 195 K with T0 equals 47 K were achieved for type II InAsSb/InAsSbP and tunneling- injection p-GaInAsSb/n-InGaAsSb lasers, respectively.
We report about light-emitting diodes (LEDs) and photodiodes (PDs) for the spectral ranges 1.8 - 2.4 micrometer and 2.9 - 4.7 micrometer based on multicomponent III-V alloys (GaInAsSb/GaAlAsSb, InAsSb/InAsSbP). High-efficiency small-dimension optoelectronic devices were applied to the design of novel set gas and moisture analyzers. Progress in development of different kinds of experimental models of the analyzers is demonstrated. Such portable sensors can be used for ecological monitoring, detecting industrial pollutants, and for various medical applications.
First observation of electroluminescence in type II broken-gap p-GaInAsSb/p-InAs single heterojunctions is reported. Intensive spontaneous emission was obtained under applied bias at T equals 77 - 300 K. Two narrow `resonant' emission bands were observed in the spectral range 3 - 5 micrometers at T equals 77 K with full width at half maximum about 1 - 2 kT. It was established that effect of unusual electroluminescence in isotype type II broken-gap p-p- heterostructure due to indirect (tunnel) radiative recombination of spatial separated 2D- electrons and holes localized in deep adjacent quantum wells at different sides of the interface. Novel tuneable mid-infrared light sources are proposed.
Semiconductor lasers and photodiodes for the 1.8-2.5 micron spectral range are described which can be used in gas analysis systems. The characteristics of pulsed lasers with output optical power reaching 1 W and low-threshold single-mode lasers are presented. The photodiodes have high quantum efficiency (0.6 without antireflection coating) and high speed or response (0.5 ns at reverse bias of several volts).
GalnAsSb/GaAlAsSb SAM APDs were fabricated and investigated.
The GaAlAsSb solid solution of the "resonant" composition (x=0.04, Eg = ?0 ) was used in the multiplication region of the devices. Large ionization rate ratio (?/? =60) and low excess noise factor ( F=Mf f=0.2) was experimentally observed.
Optoelectronic light-emitting diode-photodiode pairs based on multicomponent GaInAsSb and InAsSbP solid solutions have been researched and developed. Such pairs are able to detect absorption bands of water and gases belonging to the spectral range 1.8 - 4.8 micrometers (H2O, CO, CO2, H2S, N2O, CH4, etc.). Two-wavelength models of a new type of optical moisture meter and a methane meter was fabricated using the developed LEDs and high-efficiency photodiodes.
Staggered-''lineup type II heterojunctions have been realized in Ga In As Sb solid solutions lattice matched. to GaSb as well as ones depending on alloy composition (x1 O. 23 or XinO8O)i n Unique features of type II heterojunctions due to carrier localization and spatial separation on the interface have been experixnen tally observed by electroluminescence generation of coherent radiation and photocurrent gain. Distinctive hallmarks of the narrow-''gap GaSbGaInAsSb heterojunctions have been considered in connection with CV 1-. V and spectral response experiments. Energy band schemes of such structures have been analized. GaSbGaInAsSb heterojunctions with x 0. 80 were found to be type II misaligned ones. Novel optoelectronic devices for midIR spectral range of 1 (lasers LID''s and high-. speed photodiodes) were developed on the base of GaSb-GaInAsSb heterojunctions.
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