Visible photoluminescence （PL） has been observed from rare earth （Tm, Sm and Dy）-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-orient...Visible photoluminescence （PL） has been observed from rare earth （Tm, Sm and Dy）-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-oriented hexagonal wurtzite type structure with an average crystal size of about 80-110 nm. Room-temperature PL spectra indicate that the blue emission is due to the transition of ^1D2 to ^3F4 and ^1G4 to ^3H6 intra 4f electron of Tm^3＋, the yellow emissions of AlN：Sm are due to ^4G5/2 to the ^6HJ （J=5/2, 7/2, 9/2, 11/2） and the reddish emissions of AlN：Dy correspond to the ^4F9/2 to ^6HJ （J=5/2, 13/2, 11/2 and 9/2） and ^6Fll/2 transitions.展开更多
We investigated the quantum dots-templated growth of a（0001） GaN film on a c-plane sapphire substrate.The growth was carried out in a radio-frequency molecular beam epitaxy system.The enlargement and coalescence of ...We investigated the quantum dots-templated growth of a（0001） GaN film on a c-plane sapphire substrate.The growth was carried out in a radio-frequency molecular beam epitaxy system.The enlargement and coalescence of grains on the GaN quantum dots template was observed in the atom force microscopy images,as well as the more ideal surface morphology of the GaN epitaxial film on the quantum dots template compared with the one on the AlN buffer.The Ga polarity was confirmed by the reflected high energy electron diffraction patterns and the Raman spectra.The significant strain relaxation in the quantum dots-templated GaN film was calculated based on the Raman spectra and the X-ray rocking curves.Meanwhile,the threading dislocation density in the quantum dots-templated film was estimated to be 7.1×107cm-2,which was significantly suppressed compared with that of the AlN-buffered GaN film.The roomtemperature Hall measurement showed an electron mobility of up to 1860cm2 /V·s in the two-dimensional electron gas at the interface of the Al 0.25Ga0.75 N/GaN heterojunction.展开更多
Using the measured capacitance-voltage curves ofNi/Au Schottky contacts with different areas and the current-voltage characteristics for the A1GaAs/GaAs, A1GaN/A1N/GaN and InoAsA10.szN/A1N/GaN heterostructure field-ef...Using the measured capacitance-voltage curves ofNi/Au Schottky contacts with different areas and the current-voltage characteristics for the A1GaAs/GaAs, A1GaN/A1N/GaN and InoAsA10.szN/A1N/GaN heterostructure field-effect transistors （HFETs） at low drain-source voltage, the two-dimensional electron gas （2DEG） electron mobility for the prepared HFETs was calculated and analyzed. It was found that there is an obvious difference for the variation trend of the mobility curves between the Ⅲ-V nitride HFETs and the A1GaAs/GaAs HFETs. In the III-V nitride HFETs, the variation trend for the curves of the 2DEG electron mobility with the gate bias is closely related to the ratio of the gate length to the drainto-source distance. While the ratio of the gate length to the drainto-source distance has no effect on the variation trend for the curves of the 2DEG electron mobility with the gate bias in the A1GaAs/GaAs HFETs. The reason is attributed to the polarization Coulomb field scattering in the Ⅲ-V nitride HFETs.展开更多
The mode-locked laser diode has emerged as a promising candidate as a signal source for photonic radar systems,wireless data transmission, and frequency comb spectroscopy. They have the advantages of small size, low c...The mode-locked laser diode has emerged as a promising candidate as a signal source for photonic radar systems,wireless data transmission, and frequency comb spectroscopy. They have the advantages of small size, low cost,high reliability, and low power consumption, thanks to semiconductor technology. Mode-locked lasers based on silicon photonics advance these qualities by the use of highly advanced silicon manufacturing technology. This paper will begin by giving an overview of mode-locked laser diode literature, and then focus on mode-locked lasers on silicon. The dependence of mode-locked laser performance on design details is presented.展开更多
利用 MOCVD系统在 Al2 O3衬底上生长 In Ga N材料和 In Ga N/ Ga N量子阱结构材料。研究发现 ,In Ga N材料中 In组份几乎不受 TMG与 TMI的流量比的影响 ,而只与生长温度有关 ,生长温度由 80 0℃降低到 74 0℃ ,In组份的从 0 .2 2增加到 ...利用 MOCVD系统在 Al2 O3衬底上生长 In Ga N材料和 In Ga N/ Ga N量子阱结构材料。研究发现 ,In Ga N材料中 In组份几乎不受 TMG与 TMI的流量比的影响 ,而只与生长温度有关 ,生长温度由 80 0℃降低到 74 0℃ ,In组份的从 0 .2 2增加到 0 .4 5 ;室温 In Ga N光致发光光谱 (PL)峰全半高宽 (FWH M)为 15 .5 nm;In Ga N/ Ga N量子阱区 In Ga N的厚度 2 nm,但光荧光的强度与 10 0 nm厚 In Ga N的体材料相当。展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 50372082）.
文摘Visible photoluminescence （PL） has been observed from rare earth （Tm, Sm and Dy）-doped AlN films grown by radio-frequency magnetron reactive sputtering. X-ray diffraction indicates that the films are c-axis-oriented hexagonal wurtzite type structure with an average crystal size of about 80-110 nm. Room-temperature PL spectra indicate that the blue emission is due to the transition of ^1D2 to ^3F4 and ^1G4 to ^3H6 intra 4f electron of Tm^3＋, the yellow emissions of AlN：Sm are due to ^4G5/2 to the ^6HJ （J=5/2, 7/2, 9/2, 11/2） and the reddish emissions of AlN：Dy correspond to the ^4F9/2 to ^6HJ （J=5/2, 13/2, 11/2 and 9/2） and ^6Fll/2 transitions.
基金Project supported by the National Natural Science Foundation of China (Grant No. 1179042)
文摘We investigated the quantum dots-templated growth of a（0001） GaN film on a c-plane sapphire substrate.The growth was carried out in a radio-frequency molecular beam epitaxy system.The enlargement and coalescence of grains on the GaN quantum dots template was observed in the atom force microscopy images,as well as the more ideal surface morphology of the GaN epitaxial film on the quantum dots template compared with the one on the AlN buffer.The Ga polarity was confirmed by the reflected high energy electron diffraction patterns and the Raman spectra.The significant strain relaxation in the quantum dots-templated GaN film was calculated based on the Raman spectra and the X-ray rocking curves.Meanwhile,the threading dislocation density in the quantum dots-templated film was estimated to be 7.1×107cm-2,which was significantly suppressed compared with that of the AlN-buffered GaN film.The roomtemperature Hall measurement showed an electron mobility of up to 1860cm2 /V·s in the two-dimensional electron gas at the interface of the Al 0.25Ga0.75 N/GaN heterojunction.
基金Project supported by the National Natural Science Foundation of China(No.11174182)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20110131110005)the Graduate Independent Innovation Foundation of Shandong University,GIIFSDU(No.yzc12064)
文摘Using the measured capacitance-voltage curves ofNi/Au Schottky contacts with different areas and the current-voltage characteristics for the A1GaAs/GaAs, A1GaN/A1N/GaN and InoAsA10.szN/A1N/GaN heterostructure field-effect transistors （HFETs） at low drain-source voltage, the two-dimensional electron gas （2DEG） electron mobility for the prepared HFETs was calculated and analyzed. It was found that there is an obvious difference for the variation trend of the mobility curves between the Ⅲ-V nitride HFETs and the A1GaAs/GaAs HFETs. In the III-V nitride HFETs, the variation trend for the curves of the 2DEG electron mobility with the gate bias is closely related to the ratio of the gate length to the drainto-source distance. While the ratio of the gate length to the drainto-source distance has no effect on the variation trend for the curves of the 2DEG electron mobility with the gate bias in the A1GaAs/GaAs HFETs. The reason is attributed to the polarization Coulomb field scattering in the Ⅲ-V nitride HFETs.
基金Defense Advanced Research Projects Agency(DARPA)EPHI and DODOS contracts
文摘The mode-locked laser diode has emerged as a promising candidate as a signal source for photonic radar systems,wireless data transmission, and frequency comb spectroscopy. They have the advantages of small size, low cost,high reliability, and low power consumption, thanks to semiconductor technology. Mode-locked lasers based on silicon photonics advance these qualities by the use of highly advanced silicon manufacturing technology. This paper will begin by giving an overview of mode-locked laser diode literature, and then focus on mode-locked lasers on silicon. The dependence of mode-locked laser performance on design details is presented.
文摘利用 MOCVD系统在 Al2 O3衬底上生长 In Ga N材料和 In Ga N/ Ga N量子阱结构材料。研究发现 ,In Ga N材料中 In组份几乎不受 TMG与 TMI的流量比的影响 ,而只与生长温度有关 ,生长温度由 80 0℃降低到 74 0℃ ,In组份的从 0 .2 2增加到 0 .4 5 ;室温 In Ga N光致发光光谱 (PL)峰全半高宽 (FWH M)为 15 .5 nm;In Ga N/ Ga N量子阱区 In Ga N的厚度 2 nm,但光荧光的强度与 10 0 nm厚 In Ga N的体材料相当。
