The Experts below are selected from a list of 3705 Experts worldwide ranked by ideXlab platform
Shiou Ying Cheng - One of the best experts on this subject based on the ideXlab platform.
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an ingap Algaas gaas heterojunction bipolar transistor with zero conduction band discontinuity
Superlattices and Microstructures, 2003Co-Authors: Shiou Ying ChengAbstract:Abstract Based on the insertion of a compositionally linear-graded Algaas Layer between an InGaP emitter and GaAs base (cap) Layer, the zero conduction-band discontinuity and completely reduced potential spike at the emitter–base junction could be obtained in a heterojunction bipolar transistor. This device exhibits not only excellent dc characteristics but also better rf performances. Consequently, the designed structure provides promise in high-performance microwave device applications.
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comprehensive study of an ingap Algaas gaas heterojunction bipolar transistor with a continuous conduction band structure
Semiconductor Science and Technology, 2002Co-Authors: Shiou Ying ChengAbstract:A newly designed In0.49Ga0.51P/AlxGa1−xAs/GaAs heterojunction bipolar transistor with a continuous conduction-band structure is theoretically analysed and investigated. By introducing a compositionally linear-graded Algaas Layer into conventional InGaP/GaAs heterojunctions, a zero conduction-band discontinuity and a completely deleted potential spike can be obtained. Due to the suppression of potential spikes at the emitter/base junction, the studied device shows better dc performances such as a lower offset voltage (≤25 mV), lower saturation voltage (≤0.3 V), uniform current gain (~40) and lower turn-on voltage (~1.15 V). In addition, better ac performances are achieved. Consequently, the designed structure provides promise for high-performance analogue, digital and microwave device applications.
Af Meftah - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of the effect of the al molar fraction and thickness of an alxga1 xas window on the sensitivity of a p n n gaas solar cell to 1 mev electron irradiation
Renewable Energy, 2009Co-Authors: Af Meftah, N Sengouga, Samira KhelifiAbstract:In this paper numerical simulation has been used to predict the effect of the thickness and aluminium (Al) mole fraction of an Algaas Layer, used as a window for a p+–n–n+ GaAs solar cell under AM0 illumination and exposed to 1MeV electron irradiation. Such solar cells are used in satellites and undergo severe degradation in their performance due to induced structural defects. The irradiation-induced defects are modelled as energy levels in the energy gap of GaAs. To predict this effect, the spectral response is evaluated for different electron irradiation fluences for two types of cells. In the first a narrow Al0.31Ga0.69As window is a small part of the p+ Layer while in the second type the whole window is an AlxGa1−xAs Layer with a gradual Al mole fraction. The obtained results show that the AlxGa1−xAs window with a gradual Al mole fraction improves the resistance of the solar cell to electron irradiation especially in the short wavelengths range.
J M Zhou - One of the best experts on this subject based on the ideXlab platform.
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photoluminescence investigation of be doped npn Algaas gaas heterojunction bipolar transistor structures
Physica E-low-dimensional Systems & Nanostructures, 2005Co-Authors: X Z Shang, P J Niu, Wang Guo, Wenxin Wang, Q Huang, J M ZhouAbstract:Abstract Highly complex Npn Algaas/GaAs single heterojunction bipolar transistor (HBT) Layers with Be-doped base were investigated by photoluminescence (PL) spectroscopy. Room temperature PL shows only a broad peak of GaAs due to thermalization; 15 K PL shows five peaks. The peak at ∼1.481 eV is from a p-type GaAs base, that at ∼1.517 eV is from a low-doped GaAs Layer and that at ∼1.55 eV is from a high-doped GaAs collector. The that at ∼1.849 eV is due to bound exciton recombination in an Algaas emitter, and that at ∼1.828 eV is due to the acceptor-related transition from the Algaas Layer. The integrated intensity ratio of these two peaks can be used to investigate the Be outdiffusion behavior, thus optimizing the growth conditions of base. The DC current gain of the HBT structure with different growth conditions was found to be in good agreement with the PL results.
Samira Khelifi - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of the effect of the al molar fraction and thickness of an alxga1 xas window on the sensitivity of a p n n gaas solar cell to 1 mev electron irradiation
Renewable Energy, 2009Co-Authors: Af Meftah, N Sengouga, Samira KhelifiAbstract:In this paper numerical simulation has been used to predict the effect of the thickness and aluminium (Al) mole fraction of an Algaas Layer, used as a window for a p+–n–n+ GaAs solar cell under AM0 illumination and exposed to 1MeV electron irradiation. Such solar cells are used in satellites and undergo severe degradation in their performance due to induced structural defects. The irradiation-induced defects are modelled as energy levels in the energy gap of GaAs. To predict this effect, the spectral response is evaluated for different electron irradiation fluences for two types of cells. In the first a narrow Al0.31Ga0.69As window is a small part of the p+ Layer while in the second type the whole window is an AlxGa1−xAs Layer with a gradual Al mole fraction. The obtained results show that the AlxGa1−xAs window with a gradual Al mole fraction improves the resistance of the solar cell to electron irradiation especially in the short wavelengths range.
P D Dapkus - One of the best experts on this subject based on the ideXlab platform.
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wavelength shift of selectively oxidized al sub x o sub y Algaas gaas distributed bragg reflectors
IEEE Photonics Technology Letters, 1997Co-Authors: M H Macdougal, P D DapkusAbstract:The effect of multiple oxidations on Al/sub x/O/sub y/-GaAs DBRs and Al/sub x/O/sub y/-Algaas-GaAs DBRs is investigated. With a compositionally graded Algaas Layer, the oxide DBR remains stable under thermal stress, whereas without it, the DBR fractures. The stopband of the oxide DBR with the Algaas Layer shifts when sequenced through multiple oxidation processes, which is attributed to the vertical oxidation of the Algaas. The resonance wavelength of a Fabry-Perot cavity containing an oxide DBR shifts 6 nm after 30 min of additional oxidation at 425/spl deg/C.