Obtaining the specified electrophysical parameters of In0,01Ga0,99As:(Zn/Si) layers of solar cells in the epitaxial process from the gas phase

The paper presents the results of studying the electrophysical characteristics (conductivity and concentration of the main charge carriers) of In0.01Ga0.99As layers of the middle cascade and other structural parts of the space-based InGaP/InGaAs/Ge solar cell depending on the doping type and level specified during epitaxial growth from the gas phase by varying the supply parameters of the sources of Si and Zn impurities. The studies were performed using X-ray diffractometry, non-contact conductivity measurement, electrochemical C–V profilometry, van der Pau method (Hall effect). A linear dependence of the main charge carrier concentration in the layer on the fraction of the doping precursor in the gas mixture was confirmed. The proportionality coefficients were determined for silicon and its disilane precursor, for zinc and its dimethylzinc precursor. The results of the dopant distribution uniformity study are shown and discussed as well as the assumptions about the effects of the temperature field gradient and the stress state in the layer and substrate.

Fixturing Effects in the Thermal Modeling of Laser Cladding

Fixturing of components during laser cladding can incur significant conductive thermal losses. However, due to the surface roughness at contact, interfacial conduction is impeded. The effective contact conductivity, known as gap conductance, is much lower than the contacting material conductivities. This work investigates modeling conduction losses to fixturing bodies during laser cladding. Two laser cladding experiments are performed using contrasting fixturing schemes: one cantilevered substrate with a minimal substrate-fixture contact area and one with a substrate bolted to a work bench, with a significant substrate-fixture contact area. Using calibrated gap conductance values, error for the cantilevered fixture model decreases from 20.5% to 6.49% in the contact region, while the bench fixtured model error decreases from a range of 60–102% to 11–45%. The improvement in accuracy shows the necessity of accounting for conduction losses in the thermal modeling of laser cladding, particularly for fixturing setups with large areas of contact.

Study on Reconstruction of Fractal Rough Surfaces

The geometric topography of the engineering surfaces play key roles in many issue of engineering and science including the analysis of friction, wear, lubrication, sealing and contact conductivity, especially microcosmic surface contact, thus the characterization of surface is one of the most important topics of tribology. Using the technology of CAD/CAE, a three-dimensional solid model of the fractal surfaces was established and meshed to provide the computer models for microcosmic contact analysis between two rough surfaces in this paper.