Local doping of silicon by a point-contact microwave applicator

Livshits, Pavel; Dikhtyar, V.; Inberg, Alexandra; Shahadi, A.; Jerby, E.

doi:10.1016/j.mee.2011.04.022

Cited by 16 publications

(3 citation statements)

References 38 publications

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“…Amorphous silicon extracted from the regolith silicates for photovoltaic power generation is limited to ~1-5% efficiencies unless dopants are used to create pn junction cells. Although it is possible using microwave methods to create p-type silicon using Al dopant 64 , it is unlikely to be consistently repeatable and requires the extraction of Al which is not in the current inventory. For ISRU, we require dominantly thermal energy for heating, sintering ceramics, casting basalt, smelting minerals, etc using solar concentrators.…”

Section: Chemical Processing Of Raw Materialsmentioning

confidence: 99%

Are Self-Replicating Machines Feasible?

Ellery

2015

AIAA SPACE 2015 Conference and Exposition

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Recent developments in 3D printing technology have opened up the prospect of selfreplication in the context of robotic in-situ resource utilization (ISRU). The focus here is on 3D printing within the context of ISRU on the Moon. 3D printing technologies can print many materials including plastics, metals and ceramics for the manufacture of structures. With a judicious choice of selected in-situ raw materials, material closure can be effected while exploiting the capabilities of 3D printing. Although advancing on multiple fronts, the true value of 3D printing lies in its potential to implement universal construction. A universal constructor is a machine capable of fabricating any physical product given an appropriate program of instructions, suitable raw materials, and a source of energy in an appropriate form. Such physical products include a copy of itself -a universal constructor is by definition a self-replicating machine. A step in this direction is represented by the RepRap 3D printer that can print copies of its own plastic components. To date, there has been little effort to attempt to 3D print actuators, sensors and/or electronics. Nevertheless, the 3D printing of actuators and associated control electronics is essential, and indeed, would represent an existence proof that an appropriately designed robotic 3D printer system would constitute a universal constructor. This is consistent with theoretical kinematic models of self-replication that characterise a self-replicating machine as a computer-controlled robotic arm. To that end, I have outlined preliminary attempts to develop self-replicating machines by addressing the 3D-printable actuator and electronics aspects within the materials limits imposed by the Moon. The design of several candidate motors and potentially 3D printable electronics through vacuum tube technology are discussed. I have adopted a neural network hardware approach based on analogue circuitry as the computational medium of choice. The use of in-situ resources offers the potential construct a complete robotic infrastructure on the Moon. To that end, the full manufacturing chain from raw material to production must be considered and lunar resources offer most of the material resources required to implement a self-replicating machine. Such universal constructors can also 3D print spacecraft including structures, mechanisms, control systems, actuators, thermal management, power generation and storage, computer-based avionics and communications chains. I conclude that physical self-replicating machines are within reach. In particular, they open the potential for a complete low-cost extraterrestrial robotic manufacturing infrastructure with hitherto unimaginable benefits to humanity. Example products from this lunar infrastructure of immediate relevance include space-based geoengineering solutions in the short term and solar power satellite solutions in the long term to our current global climate crisis. Nomenclature x = number of offspring per generation n = number of generations y i = ne...

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Section: Chemical Processing Of Raw Materialsmentioning

confidence: 99%

Are Self-Replicating Machines Feasible?

Ellery

2015

AIAA SPACE 2015 Conference and Exposition

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“…al. [48,49] have introduced a new method of local doping using microwave heating called pointcontact microwave technique. A point contact microwave applicator is shown in the Fig.…”

Section: P-n Junction Formationmentioning

confidence: 99%

Prospects of Microwave Heating in Silicon Solar Cell Fabrication – A Review

Das¹

2013

IOSR-JEEE

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Solar energy is only renewable energy source that does not depend on earth's resources. Current industrial manufacturing of solar cells use manufacturing steps that have many sustainable issues. So it becomes very important to promote technologies that are more sustainable than current state of the art. This paper will look into prospects of microwave heating for silicon solar cell fabrication in this perspective. Microwave heating is very different from conventional heating techniques and application of microwave for semiconductor processing purposes has many advantages. It provides avenue to crystallisation of amorphous solids, reduction of defects, selective heating, reduction in processing time, sintering of powdered materials and so on. Sustainability analysis of microwave heating over conventional heating will be presented to judge its suitability in solar cell fabrication. Status of different technologies using microwave heating which could replace or assist in different fabrication steps of solar cells will be reviewed. Based on these reviews, possible fabrication schemes of silicon solar cells will be presented.

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“…The tip is in contact with the silicon wafer which causes local heating allowing dopant material to diffuse into the wafer within the hotspot. Experiments with Al tips on a 100–350 W microwave applicator at 2.45 GHz over 1 min doped regions of ∼1 mm diameter by ∼0.3 μm depth with concentrations of 10 19 −10 22 /cm 3 of dopant generating a pn junction barrier of 0.5–0.7 V. 22 This is a very promising approach to creating both pn junctions and lasing media but its accuracy and controllability are not established. Furthermore, P will require extraction from KREEP minerals with the imposition of complex chemical processing.…”

Section: Introductionmentioning

confidence: 99%

Generating and storing power on the moon using in situ resources

Ellery

2021

Proceedings of the Institution of Mechanical Engineers, Part G:

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The Moon Village and similar concepts are strongly reliant on in situ resource utilisation (ISRU). There is great interest in harvesting solar power using locally leveraged in situ resources as an essential facet of in situ infrastructure. Traditionally, silicon-based photovoltaic cells have been assumed, preferably manufactured in situ using a 3D printing rover, but there are major difficulties with such scenarios. Solar cells require pre-processing of regolith and solar cell manufacture. We present an alternative lunar resource leveraged-solar power production system on the Moon which can yield high conversion efficiencies – solar Fresnel lens-thermionic conversion. The thermionic vacuum tube is constructed from lunar-derived materials and NiFe asteroidal ores on the Moon. Given that the majority of energy required for ISRU is thermal, thermionic conversion exploits this energy source directly. Silicates such as anorthite can be treated with acid to yield alumina and silicic acid in solution from which pure silica can be precipitated. Pure silica when heated to high temperature yields fused silica glass which is transparent – fused silica glass may be employed to manufacture Fresnel lenses and/or mirrors. Both silica and alumina may be input to the Metalysis Fray Farthing Chen Cambridge electrolytic process to yield near pure Si and near pure Al, respectively.

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Local doping of silicon by a point-contact microwave applicator

Cited by 16 publications

References 38 publications

Are Self-Replicating Machines Feasible?

Are Self-Replicating Machines Feasible?

Prospects of Microwave Heating in Silicon Solar Cell Fabrication – A Review

Generating and storing power on the moon using in situ resources

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