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SiGe and SiGeC HBTs
Published in Chinmay K. Maiti, Introducing Technology Computer-Aided Design (TCAD), 2017
As silicon and germanium are completely miscible over the entire compositional range, bandgap engineering can be profitably used in silicon technology. The lattice constant difference of Si and Ge is about 4.17%, and if one is grown on the other below the critical thickness, the layer is strained. This strain has been used to vary the bandgap energy, band discontinuities, and effective mass to split the valley degeneracy and other electronic properties. For the last several years, silicon-germanium has shown great promise for novel device applications. In the near future, SiGe devices and Si/SiGe superlattice-based devices may even play an important role in the integration of complex electronic circuitry with optoelectronic functionality on a single integrated circuit (IC) chip. SiGe is helping to meet the challenges of the mobile communication market by providing high integration, high performance, low noise, low current consumption, and outstanding efficiency.
From 2D Planar Magnonic Crystals to 3D Magnonic Crystals
Published in Gianluca Gubbiotti, Three-Dimensional Magnonics, 2019
P. Graczyk, P. Gruszecki, S. Mamica, J. W. Kłos, M. Krawczyk, G. Gubbiotti
Bandgap engineering plays a fundamental role in electronics, photonics, and also magnonics. Magnonics offers large flexibility in tuning the environmental properties for its carriers. The classical way to engineer band structure and bandgaps is a patterning of the thin films [14, 22, 39], which, however, is very receptive for defects and changes of the magnetic properties near the edges, which, in turn, can affect SW propagation in an uncontrollable manner [20, 44]. An alternative way is ion implantation, which modifies the material properties relevant for SW propagation [3, 59] and allows also to create the fine patterns suitable for the formation of magnonic bandgaps [40]. Although it does not etch the film, the crystallographic structure and composition are significantly affected, which usually is associated with increased damping. The other interesting idea for the formation of the magnonic band structure is based on the exploitation of the vertical dynamic coupling of propagating SW in a homogeneous film with patterned elements placed in its proximity. In Ref. [2] the control of the SW propagation in a ferromagnetic stripe by a change of the magnetization orientation in the bar placed above it has been demonstrated. This mechanism was also exploited to excite and to control the phase and amplitude of propagating SWs. This idea was further extended to an array of ferromagnetic nanodots deposited over the ferromagnetic film. In this system, the magnetization dynamics pumped in the array of dots by the microwave field has been used to induce and detect short-wavelength SWs propagating in a homogeneous film [63].
Transmitters
Published in Lynne D. Green, Fiber Optic COMMUNICATIONS, 2019
Another way to create a reflecting surface is to build a heterojunction diode, either as a two–dimensional “sandwich”, or in all three dimensions: surrounding the active area on its sides as well as its top and bottom with wider bandgap materials. If the wider bandgap material has a lower index of refraction, total internal reflection can occur in the active layer, further increasing the power emitted from the LED. The use of materials of different bandgaps is referred to as bandgap engineering. The use of index differences to provide reflections is referred to as index guiding.
Performance analysis of dye-sensitized solar cells with various MgO-ZnO mixed photoanodes prepared by wet powder mixing and grinding
Published in Journal of Modern Optics, 2021
Huai-Yi Chen, Horng-Show Koo, Yung-Lin Hsu, Chun-Hung Lu
A core-shell ZnO nanowire structure synthesized at low temperature by consecutive hydrothermal growth steps was coated with MgO (Eg= ∼7.8 eV) material and assembled into DSSCs for testing [32–34]. The MgO-coated sample shows a great increase in short circuit current density (Jsc) and open-circuit voltage (Voc), with optimum device efficiency reaching 0.33% and performance much higher than the original nanowire. The improvement is mainly due to two reasons. On the one hand, the oxide layer on the nanowire allows ‘bandgap engineering’ of the device so that charge separation is optimized to inject electrons into the ZnO core. On the other hand, Ru-based dyes used in the past are less suitable for the ZnO DSSC, and this kind of dye has a tendency to agglomerate, which then limits the ability of charge transfer.
Total Ionizing Dose Effects of SiGe HBTs Induced by 60Co Gamma-Ray Irradiation
Published in Nuclear Science and Engineering, 2018
Shu-Huan Liu, Aqil Hussain, Da Li, Xiaoqiang Guo, Zhuo-Qi Li, Olarewaju Mubashiru Lawal, Jiangkun Yang, Wei Chen
SiGe heterojunction bipolar transistors (HBTs) made with bandgap engineering are able to achieve excellent performance while maintaining compatibility with conventional Si complementary metal-oxide semiconductor manufacturing, such as low noise, high speed, low cost, and irradiation hardness, without any additional process modifications. SiGe HBTs also maintain perfect work performance in very high- or low-temperature environments, etc.1–5 Therefore, SiGe HBTs have the potential to be used in some special electronic systems due to their excellent characteristics. These types of systems mainly operate in extreme environments,1 for instance, nuclear power, space, radar systems, and high-energy accelerator detector systems.1–7