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Papers by abc acb
Semiconductors, 1997
Injection heterolasers based on quantum dots grown by molecular-beam epitaxy have been investigat... more Injection heterolasers based on quantum dots grown by molecular-beam epitaxy have been investigated. It is shown that the room-temperature threshold current density can be lowered to 15 A/cm2 by decreasing the nonradiative recombination and increasing the degree of carrier localization. The density of states in structures with vertically coupled quantum dots was investigated by the electroabsorption method.
Journal of Crystal Growth, 1997
We have fabricated and studied injection lasers based on vertically coupled quantum dots (VECODs)... more We have fabricated and studied injection lasers based on vertically coupled quantum dots (VECODs). VECODs are self-organized during successive deposition of several sheets of (In,Ga)As quantum dots separated by thin GaAs spacers. VECODs are introduced in the active region of a GaAs-A1GaAs GRIN SCH lasers. Increasing the number of periods (N) in the VECOD leads to a remarkable decrease in threshold current density ( ~ 100 A/cm 2 at 300 K for N = 10). Lasing proceeds via the ground state of the quantum dots (QD) up to room temperature. Placing the QD array into an external AIGaAs--GaAs quantum well allows us to extend the range of thermal stability of threshold current density (To = 350 K) up to room temperature. Using (In,Ga)As-(A1,Ga)As VECODs in combination with high temperature growth of emitter and waveguide layers results in further reduction of threshold current density (60-80 A/cm 2, 300 K) and increase in internal quantum efficiency (70%). Room temperature continuous wave operation (light output 160 mW per mirror) and lasing via the states of QDs up to I = (6-7) Ith have been demonstrated.
Physical Review B, 1996
Alternate short-period GaAs-InAs deposition following InAs pyramid formation on a GaAs (100) surf... more Alternate short-period GaAs-InAs deposition following InAs pyramid formation on a GaAs (100) surface leads to the creation of vertically split pyramids. This splitting is driven by the energetics of the Stranski-Krastanow growth mode. The strain energy is reduced due to ...
Semiconductors, 1997
Gaseous phase epitaxy from metal organic compounds is used to obtain a low-temperature injection ... more Gaseous phase epitaxy from metal organic compounds is used to obtain a low-temperature injection laser with an active region based on In0.5Ga0.5As/GaAs quantum dots. Optimizing the growth conditions and geometric parameters of the structure has made it possible to increase the range of ultrahigh thermal stability in the threshold current (the characteristic temperature is T 0=385 K) up to 50 °C.
Superlattices and Microstructures, 1997
We have studied injection lasers based on InGaAs/GaAs vertically coupled quantum dots (QD) grown ... more We have studied injection lasers based on InGaAs/GaAs vertically coupled quantum dots (QD) grown by molecular beam epitaxy. The threshold current density decreases by one order of magnitude down to 90 A cm −2 (300 K) with an increase of the number of QD stacks (N ) up to 10. For N ≥ 3 lasing occurs via the QD ground state up to room temperature. Differential efficiency increases with N up to 50%. No change in range of high temperature stability of threshold current density (J th ) was observed, while the characteristic temperature (T 0 ) measured at 300 K increases from 60 to 120 K. Using InGaAs-AlGaAs QD with higher localization energy allowed us to decrease J th down to 60 A cm −2 and to increase the differential efficiency up to 70%.
Electronics Letters, 1998
... Using a multiline fit of the the PL spectrum it can be shown that the PL band consists of two... more ... Using a multiline fit of the the PL spectrum it can be shown that the PL band consists of two Gaussian curves ... Petersburg, Russia) SS Ruvimov and Z. Liliental-Weber (Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA) D. Bimberg (Institut ...
Semiconductors, 2003
The temperature behavior of the operation characteristics of low-threshold (the threshold current... more The temperature behavior of the operation characteristics of low-threshold (the threshold current density is below 100 A/cm2) high-efficiency (differential quantum efficiency is as high as 88%) injection laser heterostructures is studied. The active region of structures emitting in the range from 1.25 to 1.29 µm included two, five, and ten layers of InAs-GaAs quantum dots. It is shown that both the threshold current density and the external differential quantum efficiency become N-shaped functions of temperature as the distribution of carriers in the active region changes from nonequilibrium to equilibrium one.
We review the prospects for B decay studies at the LHC.
Semiconductors, 1997
Arrays of vertically aligned InGaAs quantum dots in a AlGaAs matrix have been investigated. It is... more Arrays of vertically aligned InGaAs quantum dots in a AlGaAs matrix have been investigated. It is shown that increasing the band gap of the matrix material makes it possible to increase the localization energy of quantum dots relative to the edge of the matrix band, as well as the states of the wetting layer. The use of an injection laser as the active region makes it possible to decrease the thermal filling of higher-lying states, and thereby decrease the threshold current density to 63 A/cm2 at room temperature. A model explaining the negative characteristic temperature section observed at low temperatures is proposed. The model is based on the assumption that a transition occurs from nonequilibrium to equilibrium filling of the states of the quantum dots.
Self-organized InAs quantum dots inserted in an (In,Ga)As matrix lattice matched to an InP substr... more Self-organized InAs quantum dots inserted in an (In,Ga)As matrix lattice matched to an InP substrate were used as an active region of an injection laser. Laser action was observed up to 200 K. Low threshold (11.4 A/cm2) lasing at 1.894 μm (77 K) via the quantum dot states was realized. The ground-to-excited state transition with increasing threshold gain was observed. The quantum dot material gain of the order of 104 cm-1 was estimated
Semiconductors, 2004
ABSTRACT Internal optical loss in separate-confinement laser heterostructures with an ultrawide (... more ABSTRACT Internal optical loss in separate-confinement laser heterostructures with an ultrawide (>1 smm) waveguide has been studied theoretically and experimentally. It is found that an asymmetric position of the active region in an ultrawide waveguide reduces the optical confinement factor for higher-order modes and raises the threshold electron density for these modes by 10–20%. It is shown that broadening the waveguide to above 1 µm results in a reduction of the internal optical loss only in asymmetric separate-confinement laser heterostructures. The calculated internal optical loss reaches ∼0.2 cm−1 (for λ≈1.08 µm) in an asymmetric waveguide 4 µm thick. The minimum internal optical loss has a fundamental limitation, which is determined by the loss from scattering on free carriers at the transparency carrier density in the active region. An internal optical loss of 0.34 cm−1 was attained in asymmetric separate-confinement laser heterostructures with an ultrawide (1.7 µm) waveguide, produced by MOCVD. Lasing in the fundamental transverse mode has been obtained owing to the significant difference in the threshold densities for the fundamental mode and higher-order modes. The record-breaking CW output optical power of 16 W and wallplug efficiency of 72% is obtained in 100-µm aperture lasers with a Fabry-Perot cavity length of ∼3 mm on the basis of the heterostructures produced.
Semiconductors, 1997
ABSTRACT
Semiconductors, 2004
Internal optical loss in separate-confinement laser heterostructures with an ultrawide (>1 smm) w... more Internal optical loss in separate-confinement laser heterostructures with an ultrawide (>1 smm) waveguide has been studied theoretically and experimentally. It is found that an asymmetric position of the active region in an ultrawide waveguide reduces the optical confinement factor for higher-order modes and raises the threshold electron density for these modes by 10–20%. It is shown that broadening the waveguide to above 1 µm results in a reduction of the internal optical loss only in asymmetric separate-confinement laser heterostructures. The calculated internal optical loss reaches ∼0.2 cm−1 (for λ≈1.08 µm) in an asymmetric waveguide 4 µm thick. The minimum internal optical loss has a fundamental limitation, which is determined by the loss from scattering on free carriers at the transparency carrier density in the active region. An internal optical loss of 0.34 cm−1 was attained in asymmetric separate-confinement laser heterostructures with an ultrawide (1.7 µm) waveguide, produced by MOCVD. Lasing in the fundamental transverse mode has been obtained owing to the significant difference in the threshold densities for the fundamental mode and higher-order modes. The record-breaking CW output optical power of 16 W and wallplug efficiency of 72% is obtained in 100-µm aperture lasers with a Fabry-Perot cavity length of ∼3 mm on the basis of the heterostructures produced.
Semiconductors, 2000
Wide-mesastripe InGaAsP/InP heterostructure lasers emitting at 1.3–1.5 µm were grown by metal-org... more Wide-mesastripe InGaAsP/InP heterostructure lasers emitting at 1.3–1.5 µm were grown by metal-organic chemical vapor deposition (MOCVD). Radiation-power-current and spectral characteristics of the lasers have been studied in pulsed and continuous wave (cw) operation in the temperature range of 10–60°C. The temperature of the active region of the diode laser is higher by 30–60°C than that of the copper heatsink upon saturation of the cw output power. The temperature dependence of the differential quantum efficiency strongly affects the cw output power. Output powers of 3 and 2.6 W are achieved in mesastripe lasers in cw operation, and 9 and 6.5 W in pulsed operation, at wavelengths of 1.3 and 1.5 µm, respectively.
Which of the following is not one of the stages of standardization? A) Specification B) Estimatio... more Which of the following is not one of the stages of standardization? A) Specification B) Estimation C) Acceptance D) Identification of choices Which of the following architecture for network applications was developed first? A) Client-Server architecture B) Peer-to-peer architecture C) Host-based architecture D) Client-based architecture What are three basic components of a network? A) Data link layer B) Client computer C) Circuit D) Server computer
Semiconductors, 1997
Injection heterolasers based on quantum dots grown by molecular-beam epitaxy have been investigat... more Injection heterolasers based on quantum dots grown by molecular-beam epitaxy have been investigated. It is shown that the room-temperature threshold current density can be lowered to 15 A/cm2 by decreasing the nonradiative recombination and increasing the degree of carrier localization. The density of states in structures with vertically coupled quantum dots was investigated by the electroabsorption method.
Journal of Crystal Growth, 1997
We have fabricated and studied injection lasers based on vertically coupled quantum dots (VECODs)... more We have fabricated and studied injection lasers based on vertically coupled quantum dots (VECODs). VECODs are self-organized during successive deposition of several sheets of (In,Ga)As quantum dots separated by thin GaAs spacers. VECODs are introduced in the active region of a GaAs-A1GaAs GRIN SCH lasers. Increasing the number of periods (N) in the VECOD leads to a remarkable decrease in threshold current density ( ~ 100 A/cm 2 at 300 K for N = 10). Lasing proceeds via the ground state of the quantum dots (QD) up to room temperature. Placing the QD array into an external AIGaAs--GaAs quantum well allows us to extend the range of thermal stability of threshold current density (To = 350 K) up to room temperature. Using (In,Ga)As-(A1,Ga)As VECODs in combination with high temperature growth of emitter and waveguide layers results in further reduction of threshold current density (60-80 A/cm 2, 300 K) and increase in internal quantum efficiency (70%). Room temperature continuous wave operation (light output 160 mW per mirror) and lasing via the states of QDs up to I = (6-7) Ith have been demonstrated.
Physical Review B, 1996
Alternate short-period GaAs-InAs deposition following InAs pyramid formation on a GaAs (100) surf... more Alternate short-period GaAs-InAs deposition following InAs pyramid formation on a GaAs (100) surface leads to the creation of vertically split pyramids. This splitting is driven by the energetics of the Stranski-Krastanow growth mode. The strain energy is reduced due to ...
Semiconductors, 1997
Gaseous phase epitaxy from metal organic compounds is used to obtain a low-temperature injection ... more Gaseous phase epitaxy from metal organic compounds is used to obtain a low-temperature injection laser with an active region based on In0.5Ga0.5As/GaAs quantum dots. Optimizing the growth conditions and geometric parameters of the structure has made it possible to increase the range of ultrahigh thermal stability in the threshold current (the characteristic temperature is T 0=385 K) up to 50 °C.
Superlattices and Microstructures, 1997
We have studied injection lasers based on InGaAs/GaAs vertically coupled quantum dots (QD) grown ... more We have studied injection lasers based on InGaAs/GaAs vertically coupled quantum dots (QD) grown by molecular beam epitaxy. The threshold current density decreases by one order of magnitude down to 90 A cm −2 (300 K) with an increase of the number of QD stacks (N ) up to 10. For N ≥ 3 lasing occurs via the QD ground state up to room temperature. Differential efficiency increases with N up to 50%. No change in range of high temperature stability of threshold current density (J th ) was observed, while the characteristic temperature (T 0 ) measured at 300 K increases from 60 to 120 K. Using InGaAs-AlGaAs QD with higher localization energy allowed us to decrease J th down to 60 A cm −2 and to increase the differential efficiency up to 70%.
Electronics Letters, 1998
... Using a multiline fit of the the PL spectrum it can be shown that the PL band consists of two... more ... Using a multiline fit of the the PL spectrum it can be shown that the PL band consists of two Gaussian curves ... Petersburg, Russia) SS Ruvimov and Z. Liliental-Weber (Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA) D. Bimberg (Institut ...
Semiconductors, 2003
The temperature behavior of the operation characteristics of low-threshold (the threshold current... more The temperature behavior of the operation characteristics of low-threshold (the threshold current density is below 100 A/cm2) high-efficiency (differential quantum efficiency is as high as 88%) injection laser heterostructures is studied. The active region of structures emitting in the range from 1.25 to 1.29 µm included two, five, and ten layers of InAs-GaAs quantum dots. It is shown that both the threshold current density and the external differential quantum efficiency become N-shaped functions of temperature as the distribution of carriers in the active region changes from nonequilibrium to equilibrium one.
We review the prospects for B decay studies at the LHC.
Semiconductors, 1997
Arrays of vertically aligned InGaAs quantum dots in a AlGaAs matrix have been investigated. It is... more Arrays of vertically aligned InGaAs quantum dots in a AlGaAs matrix have been investigated. It is shown that increasing the band gap of the matrix material makes it possible to increase the localization energy of quantum dots relative to the edge of the matrix band, as well as the states of the wetting layer. The use of an injection laser as the active region makes it possible to decrease the thermal filling of higher-lying states, and thereby decrease the threshold current density to 63 A/cm2 at room temperature. A model explaining the negative characteristic temperature section observed at low temperatures is proposed. The model is based on the assumption that a transition occurs from nonequilibrium to equilibrium filling of the states of the quantum dots.
Self-organized InAs quantum dots inserted in an (In,Ga)As matrix lattice matched to an InP substr... more Self-organized InAs quantum dots inserted in an (In,Ga)As matrix lattice matched to an InP substrate were used as an active region of an injection laser. Laser action was observed up to 200 K. Low threshold (11.4 A/cm2) lasing at 1.894 μm (77 K) via the quantum dot states was realized. The ground-to-excited state transition with increasing threshold gain was observed. The quantum dot material gain of the order of 104 cm-1 was estimated
Semiconductors, 2004
ABSTRACT Internal optical loss in separate-confinement laser heterostructures with an ultrawide (... more ABSTRACT Internal optical loss in separate-confinement laser heterostructures with an ultrawide (>1 smm) waveguide has been studied theoretically and experimentally. It is found that an asymmetric position of the active region in an ultrawide waveguide reduces the optical confinement factor for higher-order modes and raises the threshold electron density for these modes by 10–20%. It is shown that broadening the waveguide to above 1 µm results in a reduction of the internal optical loss only in asymmetric separate-confinement laser heterostructures. The calculated internal optical loss reaches ∼0.2 cm−1 (for λ≈1.08 µm) in an asymmetric waveguide 4 µm thick. The minimum internal optical loss has a fundamental limitation, which is determined by the loss from scattering on free carriers at the transparency carrier density in the active region. An internal optical loss of 0.34 cm−1 was attained in asymmetric separate-confinement laser heterostructures with an ultrawide (1.7 µm) waveguide, produced by MOCVD. Lasing in the fundamental transverse mode has been obtained owing to the significant difference in the threshold densities for the fundamental mode and higher-order modes. The record-breaking CW output optical power of 16 W and wallplug efficiency of 72% is obtained in 100-µm aperture lasers with a Fabry-Perot cavity length of ∼3 mm on the basis of the heterostructures produced.
Semiconductors, 1997
ABSTRACT
Semiconductors, 2004
Internal optical loss in separate-confinement laser heterostructures with an ultrawide (>1 smm) w... more Internal optical loss in separate-confinement laser heterostructures with an ultrawide (>1 smm) waveguide has been studied theoretically and experimentally. It is found that an asymmetric position of the active region in an ultrawide waveguide reduces the optical confinement factor for higher-order modes and raises the threshold electron density for these modes by 10–20%. It is shown that broadening the waveguide to above 1 µm results in a reduction of the internal optical loss only in asymmetric separate-confinement laser heterostructures. The calculated internal optical loss reaches ∼0.2 cm−1 (for λ≈1.08 µm) in an asymmetric waveguide 4 µm thick. The minimum internal optical loss has a fundamental limitation, which is determined by the loss from scattering on free carriers at the transparency carrier density in the active region. An internal optical loss of 0.34 cm−1 was attained in asymmetric separate-confinement laser heterostructures with an ultrawide (1.7 µm) waveguide, produced by MOCVD. Lasing in the fundamental transverse mode has been obtained owing to the significant difference in the threshold densities for the fundamental mode and higher-order modes. The record-breaking CW output optical power of 16 W and wallplug efficiency of 72% is obtained in 100-µm aperture lasers with a Fabry-Perot cavity length of ∼3 mm on the basis of the heterostructures produced.
Semiconductors, 2000
Wide-mesastripe InGaAsP/InP heterostructure lasers emitting at 1.3–1.5 µm were grown by metal-org... more Wide-mesastripe InGaAsP/InP heterostructure lasers emitting at 1.3–1.5 µm were grown by metal-organic chemical vapor deposition (MOCVD). Radiation-power-current and spectral characteristics of the lasers have been studied in pulsed and continuous wave (cw) operation in the temperature range of 10–60°C. The temperature of the active region of the diode laser is higher by 30–60°C than that of the copper heatsink upon saturation of the cw output power. The temperature dependence of the differential quantum efficiency strongly affects the cw output power. Output powers of 3 and 2.6 W are achieved in mesastripe lasers in cw operation, and 9 and 6.5 W in pulsed operation, at wavelengths of 1.3 and 1.5 µm, respectively.
Which of the following is not one of the stages of standardization? A) Specification B) Estimatio... more Which of the following is not one of the stages of standardization? A) Specification B) Estimation C) Acceptance D) Identification of choices Which of the following architecture for network applications was developed first? A) Client-Server architecture B) Peer-to-peer architecture C) Host-based architecture D) Client-based architecture What are three basic components of a network? A) Data link layer B) Client computer C) Circuit D) Server computer