Traditionally RF power amplifiers used Gallium Arsenide(GaAs) technology which has a well behaved and understood performance. Over the past few years Gallium Nitride(GaN) technology is replacing GaAs because GaN is mo...Traditionally RF power amplifiers used Gallium Arsenide(GaAs) technology which has a well behaved and understood performance. Over the past few years Gallium Nitride(GaN) technology is replacing GaAs because GaN is more efficient and has a higher power density resulting in higher power MMICs and FETs.Subject to system link budgets, we usually want to run a given amplifier as close to saturation as possible to minimize CAPEX costs. Running an amplifier closer to saturation causes many non-linear effects that can cause link performance degradation and interfere with other users.To better understand and quantify the differences between GaN and GaAs amplifiers and the impact of this on system performance, some amplifier and system measurements will be taken. The findings will be documented in a white paper.展开更多
A 12 Gbit/s limiting amplifier for fiber-optic transmission system is realized in a 2μm GaAs HBT technology. The whole circuit consists of an input buffer, three similar amplifier cells, an output buffer for driving ...A 12 Gbit/s limiting amplifier for fiber-optic transmission system is realized in a 2μm GaAs HBT technology. The whole circuit consists of an input buffer, three similar amplifier cells, an output buffer for driving 50 ft transmission lines and a pair of feedback networks for offset cancellation. At a positive supply voltage of 2 V and a negative supply voltage of - 2V, the power dissipation is about 280 mW. The small-signal gain is higher than 46 dB and the input dynamic range is about 40 dB with a constant single-ended output voltage swing of 400 mV. Satisfactory eye-diagrams are obtained at the bit rate of 12 Gbit/s limited by the test set-up. The chip area is 1.15 mm ×0.7 mm.展开更多
A new six-layer ohmic contact system(Ni/Ge/Au/Ge/Ni/Au)is proposed and its ohmic contact formation on n-type GaAs has been investigated.Ohmic contacts are obtained at alloying temperatures and time varying from 380℃t...A new six-layer ohmic contact system(Ni/Ge/Au/Ge/Ni/Au)is proposed and its ohmic contact formation on n-type GaAs has been investigated.Ohmic contacts are obtained at alloying temperatures and time varying from 380℃to 460℃and 50 s to 120 s,respectively.Typical contact resistance of 2.1×10^-7Ω·cm^2 is achieved at 400℃and 60 s.The surface morphology of the contacts after alloying is excellent and smooth.展开更多
In this paper, we discuss low-temperature hopping-conductivity behavior in the insulating phase, in the absence of a magnetic field. We conduct a theoretical study of the crossover from hopping to activated transport ...In this paper, we discuss low-temperature hopping-conductivity behavior in the insulating phase, in the absence of a magnetic field. We conduct a theoretical study of the crossover from hopping to activated transport in a GaAs two-dimensional hole system at low temperatures, finding that a crossover takes place from the Efros-Shklovskii variable-range hopping(VRH)regime to an activated regime in this system. This conductivity behavior in p-GaAs quantum wells is qualitatively consistent with the laws laid down in theories of localized electron interactions. Given sufficiently strong interactions, the holes in the localized states are able to hop collectively.展开更多
文摘Traditionally RF power amplifiers used Gallium Arsenide(GaAs) technology which has a well behaved and understood performance. Over the past few years Gallium Nitride(GaN) technology is replacing GaAs because GaN is more efficient and has a higher power density resulting in higher power MMICs and FETs.Subject to system link budgets, we usually want to run a given amplifier as close to saturation as possible to minimize CAPEX costs. Running an amplifier closer to saturation causes many non-linear effects that can cause link performance degradation and interfere with other users.To better understand and quantify the differences between GaN and GaAs amplifiers and the impact of this on system performance, some amplifier and system measurements will be taken. The findings will be documented in a white paper.
文摘采用全固态分子束外延(MBE)技术在InP衬底上生长InGaAsP材料,获得了与衬底之间没有失配位错且界面质量和发光质量较好的1.05 eV的InGaAsP材料。在此基础上,分别在InP衬底上生长InGaAsP单结太阳能电池以及GaAs衬底上生长GaInP/GaAs双结太阳能电池。利用晶圆键合技术将两个分立的电池键合制备成一个GaInP/GaAs/InGaAsP三结太阳电池。在地面光谱AM1.5G(Air Mass 1.5 Global)太阳模拟器下,GaInP/GaAs/InGaAsP晶圆键合太阳电池的转换效率为30.6%,聚光下获得了34%的效率。研究结果表明,MBE能够生长出材料质量佳的InGaAsP材料,室温晶圆键合技术在制备多结太阳能电池方面具有很大的潜力。
文摘A 12 Gbit/s limiting amplifier for fiber-optic transmission system is realized in a 2μm GaAs HBT technology. The whole circuit consists of an input buffer, three similar amplifier cells, an output buffer for driving 50 ft transmission lines and a pair of feedback networks for offset cancellation. At a positive supply voltage of 2 V and a negative supply voltage of - 2V, the power dissipation is about 280 mW. The small-signal gain is higher than 46 dB and the input dynamic range is about 40 dB with a constant single-ended output voltage swing of 400 mV. Satisfactory eye-diagrams are obtained at the bit rate of 12 Gbit/s limited by the test set-up. The chip area is 1.15 mm ×0.7 mm.
文摘A new six-layer ohmic contact system(Ni/Ge/Au/Ge/Ni/Au)is proposed and its ohmic contact formation on n-type GaAs has been investigated.Ohmic contacts are obtained at alloying temperatures and time varying from 380℃to 460℃and 50 s to 120 s,respectively.Typical contact resistance of 2.1×10^-7Ω·cm^2 is achieved at 400℃and 60 s.The surface morphology of the contacts after alloying is excellent and smooth.
文摘In this paper, we discuss low-temperature hopping-conductivity behavior in the insulating phase, in the absence of a magnetic field. We conduct a theoretical study of the crossover from hopping to activated transport in a GaAs two-dimensional hole system at low temperatures, finding that a crossover takes place from the Efros-Shklovskii variable-range hopping(VRH)regime to an activated regime in this system. This conductivity behavior in p-GaAs quantum wells is qualitatively consistent with the laws laid down in theories of localized electron interactions. Given sufficiently strong interactions, the holes in the localized states are able to hop collectively.
