The InGaAs/InAIAs/InP high electron mobility transistor （HEM：F） structures with lattice-matched and pseudo- morphic channels are grown by gas source molecular beam epitaxy. Effects of Si ^-doping condition and grow...The InGaAs/InAIAs/InP high electron mobility transistor （HEM：F） structures with lattice-matched and pseudo- morphic channels are grown by gas source molecular beam epitaxy. Effects of Si ^-doping condition and growth interruption on the electrical properties are investigated by changing the Si-cell temperature, doping time and growth process. It is found that the optimal Si ^-doping concentration （Nd） is about 5.0 x 1012 cm-2 and the use of growth interruption has a dramatic effect on the improvement of electrical properties. The material structure and crystal interface are analyzed by secondary ion mass spectroscopy and high resolution transmission elec- tron microscopy. An InGaAs/InAiAs/InP HEMT device with a gate length of lOOnm is fabricated. The device presents good pinch-off characteristics and the kink-effect of the device is trifling. In addition, the device exhibits fT = 249 GHa and fmax 〉 400 GHz.展开更多
The structure of In P-based In_xGa_（1-x） As/In0.52Al0.48 As pseudomorphic high electron mobility transistor（PHEMT）was optimized in detail.Effects of growth temperature,growth interruption time,Si δ-doping conditi...The structure of In P-based In_xGa_（1-x） As/In0.52Al0.48 As pseudomorphic high electron mobility transistor（PHEMT）was optimized in detail.Effects of growth temperature,growth interruption time,Si δ-doping condition,channel thickness and In content,and inserted Al As monolayer（ML） on the two-dimensional electron gas（2DEG） performance were investigated carefully.It was found that the use of the inserted Al As monolayer has an enhancement effect on the mobility due to the reduction of interface roughness and the suppression of Si movement.With optimization of the growth parameters,the structures composed of a 10 nm thick In0.75Ga0.25 As channel layer and a 3 nm thick Al As/In0.52Al0.48 As superlattices spacer layer exhibited electron mobilities as high as 12500 cm^2·V-1·s^（-1）（300 K） and 53500 cm^2·V~（-1_·s^（-1）（77 K） and the corresponding sheet carrier concentrations（Ns） of 2.8×10^（12）cm^（-2）and 2.9×1012cm^（-2）,respectively.To the best of the authors＇ knowledge,this is the highest reported room temperature mobility for In P-based HEMTs with a spacer of 3 nm to date.展开更多
Carbon-doped In Ga As Bi films on In P:Fe(100)substrates have been grown by gas source molecular beam epitaxy(GSMBE).The electrical properties and non-alloyed Ti/Pt/Au contact resistance of n-type carbon-doped In Ga A...Carbon-doped In Ga As Bi films on In P:Fe(100)substrates have been grown by gas source molecular beam epitaxy(GSMBE).The electrical properties and non-alloyed Ti/Pt/Au contact resistance of n-type carbon-doped In Ga As Bi films were characterized by Van der Pauw-Hall measurement and transmission line method(TLM)with and without rapid thermal annealing(RTA).It was found that the specific contact resistance decreases gradually with the increase of carrier concentration.The electron concentration exhibits a sharp increase,and the specific contact resistance shows a noticeable reduction after RTA.With RTA,the In Ga As Bi film grown under CBr4 supply pressure of 0.18 Torr exhibited a high electron concentration of 1.6×10^(21) cm^(-3) and achieved an ultra-low specific contact resistance of 1×10^(-8)Ω·cm^(2),revealing that contact resistance depends greatly on the tunneling effect.展开更多
A facile citric acid assisted sol-gel combustion method was performed to synthesize cobalt chromite(CoCr2O4)ceramic pigment.The effect of the annealing temperature on structure,morphologies,and optical properties of t...A facile citric acid assisted sol-gel combustion method was performed to synthesize cobalt chromite(CoCr2O4)ceramic pigment.The effect of the annealing temperature on structure,morphologies,and optical properties of the prepared CoCr2O4 pigments were systematically studied by thermogravimetry,differential thermal analysis,X-ray diffraction(XRD)and field emission scanning electron microscope(FESEM).The results show that CoCr2O4 spinel crystal was achieved after heat treatment of the as-burnt powder at a relatively low temperature(400°C)and the average crystallite size of the CoCr2O4 pigment increased with the annealing temperature.Furthermore,on the CIE parameters of CoCr2O4 pigment,a*and b*values became much more negative with the annealing temperature due to much more Co^2+ions located in tetrahedral sites and much more Cr^3+ions located in octahedral sites.Finally,the measured solar absorptance indicates that this ceramic pigment is expected to fabricate the color paint coating for solar absorber application.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 61434006
文摘The InGaAs/InAIAs/InP high electron mobility transistor （HEM：F） structures with lattice-matched and pseudo- morphic channels are grown by gas source molecular beam epitaxy. Effects of Si ^-doping condition and growth interruption on the electrical properties are investigated by changing the Si-cell temperature, doping time and growth process. It is found that the optimal Si ^-doping concentration （Nd） is about 5.0 x 1012 cm-2 and the use of growth interruption has a dramatic effect on the improvement of electrical properties. The material structure and crystal interface are analyzed by secondary ion mass spectroscopy and high resolution transmission elec- tron microscopy. An InGaAs/InAiAs/InP HEMT device with a gate length of lOOnm is fabricated. The device presents good pinch-off characteristics and the kink-effect of the device is trifling. In addition, the device exhibits fT = 249 GHa and fmax 〉 400 GHz.
基金Project supported by the National Natural Science Foundation of China(Grant No.61434006)
文摘The structure of In P-based In_xGa_（1-x） As/In0.52Al0.48 As pseudomorphic high electron mobility transistor（PHEMT）was optimized in detail.Effects of growth temperature,growth interruption time,Si δ-doping condition,channel thickness and In content,and inserted Al As monolayer（ML） on the two-dimensional electron gas（2DEG） performance were investigated carefully.It was found that the use of the inserted Al As monolayer has an enhancement effect on the mobility due to the reduction of interface roughness and the suppression of Si movement.With optimization of the growth parameters,the structures composed of a 10 nm thick In0.75Ga0.25 As channel layer and a 3 nm thick Al As/In0.52Al0.48 As superlattices spacer layer exhibited electron mobilities as high as 12500 cm^2·V-1·s^（-1）（300 K） and 53500 cm^2·V~（-1_·s^（-1）（77 K） and the corresponding sheet carrier concentrations（Ns） of 2.8×10^（12）cm^（-2）and 2.9×1012cm^（-2）,respectively.To the best of the authors＇ knowledge,this is the highest reported room temperature mobility for In P-based HEMTs with a spacer of 3 nm to date.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11705277 and 61434006)the Project of Hubei University of Arts and Science(Grant No.XK2019053)。
文摘Carbon-doped In Ga As Bi films on In P:Fe(100)substrates have been grown by gas source molecular beam epitaxy(GSMBE).The electrical properties and non-alloyed Ti/Pt/Au contact resistance of n-type carbon-doped In Ga As Bi films were characterized by Van der Pauw-Hall measurement and transmission line method(TLM)with and without rapid thermal annealing(RTA).It was found that the specific contact resistance decreases gradually with the increase of carrier concentration.The electron concentration exhibits a sharp increase,and the specific contact resistance shows a noticeable reduction after RTA.With RTA,the In Ga As Bi film grown under CBr4 supply pressure of 0.18 Torr exhibited a high electron concentration of 1.6×10^(21) cm^(-3) and achieved an ultra-low specific contact resistance of 1×10^(-8)Ω·cm^(2),revealing that contact resistance depends greatly on the tunneling effect.
基金This work has been supported by the Project of Hubei University of Arts and Science(Nos.XK2020043 and XK2019052)the National Natural Science Foundation of China(No.11705277)the Development and Achievements Transformation Project and Hubei Superior and Distinctive Discipline Group of“Mechatronics and Automobiles”(No.XKQ2018001).
文摘A facile citric acid assisted sol-gel combustion method was performed to synthesize cobalt chromite(CoCr2O4)ceramic pigment.The effect of the annealing temperature on structure,morphologies,and optical properties of the prepared CoCr2O4 pigments were systematically studied by thermogravimetry,differential thermal analysis,X-ray diffraction(XRD)and field emission scanning electron microscope(FESEM).The results show that CoCr2O4 spinel crystal was achieved after heat treatment of the as-burnt powder at a relatively low temperature(400°C)and the average crystallite size of the CoCr2O4 pigment increased with the annealing temperature.Furthermore,on the CIE parameters of CoCr2O4 pigment,a*and b*values became much more negative with the annealing temperature due to much more Co^2+ions located in tetrahedral sites and much more Cr^3+ions located in octahedral sites.Finally,the measured solar absorptance indicates that this ceramic pigment is expected to fabricate the color paint coating for solar absorber application.
