The epitaxial growth of a high-quality silicon layer on double-layer porous silicon by ultra-high vacuum/chemical vapour deposition has been reported. The two-step anodization process results in a double-layer porous ...The epitaxial growth of a high-quality silicon layer on double-layer porous silicon by ultra-high vacuum/chemical vapour deposition has been reported. The two-step anodization process results in a double-layer porous silicon structure with a different porosity. This double-layer porous silicon structure and an extended low-temperature annealing in a vacuum system was found to be helpful in subsequent silicon epitaxial growth. X-ray diffraction,cross-sectional transmission electron microscopy and spreading resistance testing were used in this work to study the properties of epitaxial silicon layers grown on the double-layer porous silicon. The results show that the epitaxial silicon layer is of good crystallinity and the same orientation with the silicon substrate and the porous silicon layer.展开更多
Ga_(0.51)In_(0.49)P/(In)GaAs/GaAs heterostructure is regarded as an excellent candidate for two dimensional hole gas system as it has a large valence band offset ratio.In this paper,we report the hole mobility in GaIn...Ga_(0.51)In_(0.49)P/(In)GaAs/GaAs heterostructure is regarded as an excellent candidate for two dimensional hole gas system as it has a large valence band offset ratio.In this paper,we report the hole mobility in GaInP/GaAs and GaInP/In_(0.20)G_(0.80)As/GaAs p-type modulation doped heterostructures grown by gas source molecular beam epitaxy with different p-channels and doping methods.The influences of Be:GaAs cap layer,δ-doping,and strained InGaAs p-channel on hole mobility are discussed,and qualitatively explained by the ionized impurity scattering mechanism.Finally,it was shown that the improvement of hole mobility could be achieved by the δ-doping method combined with strained InGaAs channel.展开更多
Device quality InAsP/InGaAsP strained multiquantum-well(MQW)structures are successfully grown by using gas source molecular beam epitaxy method.The grown MQW and InGaAsP quanternary alloy are characterized by using x-...Device quality InAsP/InGaAsP strained multiquantum-well(MQW)structures are successfully grown by using gas source molecular beam epitaxy method.The grown MQW and InGaAsP quanternary alloy are characterized by using x-ray diffraction,room temperature photoluminescence measurements,confirming that optimum growth condition and high quality material have been obtained for device application.The grown laser structures are processed into ridge waveguide lasers.A threshold current as low as 16mA at 250C for 300μm long device has been obtained.Temperature-dependent light-current measurement shows a characteristic temperature of75K.展开更多
This paper reports the improved performance of the lattice-matched N-p^(+)-n In_(0.49)Ga_(0.51)P/GaAs heterojunction bipolar transistors(HBTs)with undoped spacers grown by the gas source molecular beam epitaxy.A 600&#...This paper reports the improved performance of the lattice-matched N-p^(+)-n In_(0.49)Ga_(0.51)P/GaAs heterojunction bipolar transistors(HBTs)with undoped spacers grown by the gas source molecular beam epitaxy.A 600ÅGaAs base doped with beryllium at 3 × 1019cm^(-3) and a 1000Å In_(0.49)Ga_(0.51)P emitter doped with silicon at 3 × 1017cm^(-3) have been grown.On both sides of the base,the 50Åundoped GaAs spacers were grown.Devices with emitter area of 100× 100μm^(2) were fabricated by using selective wet chemical etching technique.The measured results of HBTs reveal cood junction characteristics,and the common-emitter current gain reaches 320 at the collector current density of 280 A/cm^(2).展开更多
Conduction band non-parabolicity is taken into account and a numerical method is proposed to calculate the electron subband energy levels and corresponding wave functions in the active region of quantum cascade lasers...Conduction band non-parabolicity is taken into account and a numerical method is proposed to calculate the electron subband energy levels and corresponding wave functions in the active region of quantum cascade lasers.For a coupled double-well vertical transition mode active region,the calculated △E21=32 meV,△E32=270 meV correspond,respectively,to the energy of an optical phonon and that of a photon at wavelength λ=4.5μm.For a coupled triple-well vertical transition active region,the calculated △E21=32.4 meV,△E32=250 meV correspond to the energy of an optical phonon and the photon energy at wavelength λ=5.0μm.展开更多
Gas source molecular beam epitaxy grown InP-based InAlAs/InGaAs quantum well infrared photodetectors operating at 3—5 pm atmosphere window have been fabricated;their structural,electrical and optical characteristics ...Gas source molecular beam epitaxy grown InP-based InAlAs/InGaAs quantum well infrared photodetectors operating at 3—5 pm atmosphere window have been fabricated;their structural,electrical and optical characteristics have been investigated.The detectors show peak response wavelength Ap at 3.85μm,with spectral width AX/Xp of 4.6%and 7.2%at 1 and 5 V bias voltages,respectively.Very low dark current of the detectors has been observed.At 2 V bias the dark current is below InA at 77K and remains low value of 10 nA at 150 K.The background limited infrared performance temperature Tblip as high as 165 K has been measured.展开更多
Calculating the refractive index dispersions considering the influence of doping concentration on refractive indices,we have illustrated the heavily doped contact layers,n=1×10^(19)cm^(-3)forλ~9μm,and n~1 x 10^...Calculating the refractive index dispersions considering the influence of doping concentration on refractive indices,we have illustrated the heavily doped contact layers,n=1×10^(19)cm^(-3)forλ~9μm,and n~1 x 10^(20)cm^(-3)forλ=5μm quantum cascade lasers,to suppress the refractive indices and get sufficient optical confinement.By calculating the transmission of energies through a graded gap superlattice,it is demonstrated that for energies E1 and E2(the two lower states)the electrons can easily get through the graded gap superlattice.While for energy E3 the graded gap superlattice creates a minigap(the transmission of the energies E1 and E2 is 102 times more than that of E3).In this way,the electrical confinement can be achieved.展开更多
The Schottky contact characteristics of Cr on n-and p-type 6H-SiC have been investigated by using I-V and C-V methods,and the barrier heights and ideality factors have been measured.Results obtained show that Cr is al...The Schottky contact characteristics of Cr on n-and p-type 6H-SiC have been investigated by using I-V and C-V methods,and the barrier heights and ideality factors have been measured.Results obtained show that Cr is also an appropriate metal to form Schottky junction on n type 6H-SiC,as the barrier height of~1 eV is moderate for both low forward turn on voltage and low backward leakage current in device applications.However,the interfacial properties of Cr to p type 6H-SiC results in nonideal Schottky junctions.展开更多
The relationship between well width and subband energy as well as response wavelength of the InAlAs/InGaAs multi-quantum well structures have been calculated for the design of the devices by using Kronig-Penney model....The relationship between well width and subband energy as well as response wavelength of the InAlAs/InGaAs multi-quantum well structures have been calculated for the design of the devices by using Kronig-Penney model.By using gas source molecular beam epitaxy grown InAlAs/InGaAs quantum well infrared photodetector(QWIP)materials have been used to fabricate QWIP devices with 3-5μm band.Ⅰ-Ⅴ characteristics and response spectra of the devices have been measured.Results show that the devices have peak response at 4.0μm with full width of half maximum of about 29.5meV.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.69876007。
文摘The epitaxial growth of a high-quality silicon layer on double-layer porous silicon by ultra-high vacuum/chemical vapour deposition has been reported. The two-step anodization process results in a double-layer porous silicon structure with a different porosity. This double-layer porous silicon structure and an extended low-temperature annealing in a vacuum system was found to be helpful in subsequent silicon epitaxial growth. X-ray diffraction,cross-sectional transmission electron microscopy and spreading resistance testing were used in this work to study the properties of epitaxial silicon layers grown on the double-layer porous silicon. The results show that the epitaxial silicon layer is of good crystallinity and the same orientation with the silicon substrate and the porous silicon layer.
基金Supported in part by the Chinese Academy of Sciences,contract number DY95608030517.
文摘Ga_(0.51)In_(0.49)P/(In)GaAs/GaAs heterostructure is regarded as an excellent candidate for two dimensional hole gas system as it has a large valence band offset ratio.In this paper,we report the hole mobility in GaInP/GaAs and GaInP/In_(0.20)G_(0.80)As/GaAs p-type modulation doped heterostructures grown by gas source molecular beam epitaxy with different p-channels and doping methods.The influences of Be:GaAs cap layer,δ-doping,and strained InGaAs p-channel on hole mobility are discussed,and qualitatively explained by the ionized impurity scattering mechanism.Finally,it was shown that the improvement of hole mobility could be achieved by the δ-doping method combined with strained InGaAs channel.
基金Supported by the Key Project for Fundamental Study of Chinese Academy of Sciences under Grant No.KT951-B1-706-3.
文摘Device quality InAsP/InGaAsP strained multiquantum-well(MQW)structures are successfully grown by using gas source molecular beam epitaxy method.The grown MQW and InGaAsP quanternary alloy are characterized by using x-ray diffraction,room temperature photoluminescence measurements,confirming that optimum growth condition and high quality material have been obtained for device application.The grown laser structures are processed into ridge waveguide lasers.A threshold current as low as 16mA at 250C for 300μm long device has been obtained.Temperature-dependent light-current measurement shows a characteristic temperature of75K.
基金Supported by the Chinese Academy of Sciences under Grant No.DY95608030517.
文摘This paper reports the improved performance of the lattice-matched N-p^(+)-n In_(0.49)Ga_(0.51)P/GaAs heterojunction bipolar transistors(HBTs)with undoped spacers grown by the gas source molecular beam epitaxy.A 600ÅGaAs base doped with beryllium at 3 × 1019cm^(-3) and a 1000Å In_(0.49)Ga_(0.51)P emitter doped with silicon at 3 × 1017cm^(-3) have been grown.On both sides of the base,the 50Åundoped GaAs spacers were grown.Devices with emitter area of 100× 100μm^(2) were fabricated by using selective wet chemical etching technique.The measured results of HBTs reveal cood junction characteristics,and the common-emitter current gain reaches 320 at the collector current density of 280 A/cm^(2).
基金Supported in part by the Chinese Academy of Sciences Contract No.KJ951-B1-706-01.
文摘Conduction band non-parabolicity is taken into account and a numerical method is proposed to calculate the electron subband energy levels and corresponding wave functions in the active region of quantum cascade lasers.For a coupled double-well vertical transition mode active region,the calculated △E21=32 meV,△E32=270 meV correspond,respectively,to the energy of an optical phonon and that of a photon at wavelength λ=4.5μm.For a coupled triple-well vertical transition active region,the calculated △E21=32.4 meV,△E32=250 meV correspond to the energy of an optical phonon and the photon energy at wavelength λ=5.0μm.
基金Supported by the National Natural Science Foundation of China under Grant No.69677022.
文摘Gas source molecular beam epitaxy grown InP-based InAlAs/InGaAs quantum well infrared photodetectors operating at 3—5 pm atmosphere window have been fabricated;their structural,electrical and optical characteristics have been investigated.The detectors show peak response wavelength Ap at 3.85μm,with spectral width AX/Xp of 4.6%and 7.2%at 1 and 5 V bias voltages,respectively.Very low dark current of the detectors has been observed.At 2 V bias the dark current is below InA at 77K and remains low value of 10 nA at 150 K.The background limited infrared performance temperature Tblip as high as 165 K has been measured.
基金the Chinese Academy of Sciences under Contract No.KJ951-B1-706-01.
文摘Calculating the refractive index dispersions considering the influence of doping concentration on refractive indices,we have illustrated the heavily doped contact layers,n=1×10^(19)cm^(-3)forλ~9μm,and n~1 x 10^(20)cm^(-3)forλ=5μm quantum cascade lasers,to suppress the refractive indices and get sufficient optical confinement.By calculating the transmission of energies through a graded gap superlattice,it is demonstrated that for energies E1 and E2(the two lower states)the electrons can easily get through the graded gap superlattice.While for energy E3 the graded gap superlattice creates a minigap(the transmission of the energies E1 and E2 is 102 times more than that of E3).In this way,the electrical confinement can be achieved.
文摘The Schottky contact characteristics of Cr on n-and p-type 6H-SiC have been investigated by using I-V and C-V methods,and the barrier heights and ideality factors have been measured.Results obtained show that Cr is also an appropriate metal to form Schottky junction on n type 6H-SiC,as the barrier height of~1 eV is moderate for both low forward turn on voltage and low backward leakage current in device applications.However,the interfacial properties of Cr to p type 6H-SiC results in nonideal Schottky junctions.
文摘The relationship between well width and subband energy as well as response wavelength of the InAlAs/InGaAs multi-quantum well structures have been calculated for the design of the devices by using Kronig-Penney model.By using gas source molecular beam epitaxy grown InAlAs/InGaAs quantum well infrared photodetector(QWIP)materials have been used to fabricate QWIP devices with 3-5μm band.Ⅰ-Ⅴ characteristics and response spectra of the devices have been measured.Results show that the devices have peak response at 4.0μm with full width of half maximum of about 29.5meV.
