2019年3月25日星期一

Generation of difference-frequency radiation in the far- and mid-IR ranges in a two-chip laser based on gallium arsenide on a germanium substrate

The possibility of efficient generation of difference-frequency radiation in the far- and mid-IR ranges in a two-chip laser based on gallium arsenide grown on a germanium substrate is considered. It is shown that a laser with a waveguide of width 100 μm emitting 1 W in the near-IR range can generate ≈40 μW at the difference frequency in the region 5—50 THz at room temperature.


Source:IOPscience

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2019年3月18日星期一

Temperature Dependence of the Photoconductive Lifetime in N-Type Gallium Arsenide Diffused with Copper

Temperature dependence of the photoconductive lifetime has been studied in the temperature range 100°–360°K on n-type gallium arsenide partially compensated with copper. It is confirmed that in n-type gallium arsenide the electron lifetime is determined by the presence of two different levels: one is a recombination level at about the middle of the band gap and the other is an acceptor level near the valence band. The electron capture-cross-section of the acceptor level is estimated to be 10-22-2×10-23 cm2. From the magnitude of the hole capture-cross-section, the recombination level is presumed to be a donor.



Source:IOPscience

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2019年3月13日星期三

Degradation of uncooled electron-pumped gallium arsenide lasers

An investigation was made of the degradation of electron-pumped gallium arsenide lasers operating at room temperature. One of the reasons for the degradation of these uncooled lasers was (in contrast to the cooled devices) an increase in the density of dislocations in the active region of a crystal because of the greater plasticity at higher temperatures.


Source:IOPscience

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2019年3月4日星期一

Influence of doping density and deposition technology on ohmic contacts to n-type gallium arsenide

A systematic series of measurements of specific contact resistance has been made for heat treated gold-germanium contacts to epitaxial n-type gallium arsenide. An inverse relationship is found between the specific contact resistance and the donor concentration of the original gallium arsenide for donor concentrations up to 4*1017 cm-3. Above this concentration the specific contact resistance becomes independent of doping. This result, together with measurements of the temperature dependence of specific contact resistance, confirms the 'two-barrier' models of the specific contact resistance, and specifically excludes the spreading resistance model. Further experiments show that the numerical values of specific contact resistance depend on whether the gold-germanium layer is deposited by sputtering or by thermal evaporation.


Source:IOPscience

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2019年2月18日星期一

Desorption of the Excess Gallium Atoms at the Surface of Gallium Arsenide and Application to Atomic Layer Epitaxy

Desorption of the excess gallium atoms at the gallium arsenide surface is studied by means of an alternating source supply method. The activation energy of the desorption is estimated to be 2.5 eV, which is substantially smaller than that of the sublimation of Ga atoms from GaAs crystal (4.9 eV). Using this desorption behavior, the possibility of atomic layer epitaxy by molecular beam epitaxy is examined.


Source:IOPscience

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2019年2月12日星期二

Photoluminescence from epitaxial and polycrystalline layers of gallium arsenide

Photoluminescence has been observed from layers of zinc-doped gallium arsenide, grown by vapour transport both epitaxially on single-crystal gallium arsenide and as polycrystalline layers on sapphire substrates. The correlation between the wavelength of maximum photoluminescence and the hole concentration is in agreement with previous work on single crystals. The technique can be used for the measurement of doping levels in single-crystal or polycrystalline material, over the doping range 1018 to 1020 cm−3, accurate to within a factor of three.


Source:IOPscience

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2019年2月1日星期五

The Properties of the Interface between Gallium Arsenide and Silicon Oxides

The MOS characteristics of gallium arsenide were investigated using silicon monoxide and dioxide as insulators. The band scheme was nearly flat at the surface of gallium arsenide covered by these oxides. At the interface, there were several kinds of surface state whose levels were located at 0.05, 0.2, 0.4, 0.55 and 0.65 eV below the conduction band edge respectively. Densities of these states were estimated as about 2~5×1011/cm2.



Source:IOPscience

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