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Title: High-aspect-ratio silicon-cell metallization technical status report. Final report

Abstract

Two features of the silicon concentrator solar cell are addressed which affect output at high concentration levels. The first is the development of narrow but high electroplated grid lines with improved conductivity. The object is a reduction in cell series resistance without increase in shadowing. This goal is accomplished by electroplating through a thick photo resist mask to produce lines .7 mil wide by .7 mil high. Advance pulse plating techniques are combined with pure silver plating baths to produce a deposit conductivity equal to the bulk silver conductivity (a 1.5 to 2 X improvement over conventional silver plating). The second feature is a double diffused selectively textured front surface. This development employs a deep diffusion in the silicon under the grid lines. Only the non grid line open area is selectively texture etched removing the deep junction. This open textured area is then given a second shallow diffusion for optimum cell efficiency. This selective procedure maintains the original highly polished wafer surface under the grid lines so that high resolution narrow grid lines are possible. The double diffusion protects the junction from metal diffusion while enabling the optimum shallow junction in the illuminated regions. Combining these two features hasmore » produced a large area concentrator cells (8 cm/sup 2/) with peak efficiency above 16% and exhibiting a broad peak efficiency extending from 50 to 175 suns above 15%.« less

Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (USA); Boeing Aerospace Co., Seattle, WA (USA)
OSTI Identifier:
5428704
Report Number(s):
SAND-81-7033
ON: DE82011687
DOE Contract Number:
AC04-76DP00789
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of document are illegible
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; CONCENTRATOR SOLAR CELLS; ELECTRIC CONTACTS; ETCHING; GRIDS; SILICON SOLAR CELLS; SILVER; ELECTROPLATING; ASPECT RATIO; DESIGN; DIFFUSION; EFFICIENCY; ELECTRIC CONDUCTIVITY; HYDRAZINE; MASKING; OPTIMIZATION; ROUGHNESS; TEXTURE; DEPOSITION; DIRECT ENERGY CONVERTERS; ELECTRICAL EQUIPMENT; ELECTRICAL PROPERTIES; ELECTRODEPOSITION; ELECTRODES; ELECTROLYSIS; ELEMENTS; EQUIPMENT; LYSIS; METALS; NITROGEN COMPOUNDS; PHOTOELECTRIC CELLS; PHOTOVOLTAIC CELLS; PHYSICAL PROPERTIES; PLATING; SOLAR CELLS; SOLAR EQUIPMENT; SURFACE COATING; SURFACE FINISHING; SURFACE PROPERTIES; TRANSITION ELEMENTS; 140501* - Solar Energy Conversion- Photovoltaic Conversion

Citation Formats

Not Available. High-aspect-ratio silicon-cell metallization technical status report. Final report. United States: N. p., 1982. Web. doi:10.2172/5428704.
Not Available. High-aspect-ratio silicon-cell metallization technical status report. Final report. United States. doi:10.2172/5428704.
Not Available. 1982. "High-aspect-ratio silicon-cell metallization technical status report. Final report". United States. doi:10.2172/5428704. https://www.osti.gov/servlets/purl/5428704.
@article{osti_5428704,
title = {High-aspect-ratio silicon-cell metallization technical status report. Final report},
author = {Not Available},
abstractNote = {Two features of the silicon concentrator solar cell are addressed which affect output at high concentration levels. The first is the development of narrow but high electroplated grid lines with improved conductivity. The object is a reduction in cell series resistance without increase in shadowing. This goal is accomplished by electroplating through a thick photo resist mask to produce lines .7 mil wide by .7 mil high. Advance pulse plating techniques are combined with pure silver plating baths to produce a deposit conductivity equal to the bulk silver conductivity (a 1.5 to 2 X improvement over conventional silver plating). The second feature is a double diffused selectively textured front surface. This development employs a deep diffusion in the silicon under the grid lines. Only the non grid line open area is selectively texture etched removing the deep junction. This open textured area is then given a second shallow diffusion for optimum cell efficiency. This selective procedure maintains the original highly polished wafer surface under the grid lines so that high resolution narrow grid lines are possible. The double diffusion protects the junction from metal diffusion while enabling the optimum shallow junction in the illuminated regions. Combining these two features has produced a large area concentrator cells (8 cm/sup 2/) with peak efficiency above 16% and exhibiting a broad peak efficiency extending from 50 to 175 suns above 15%.},
doi = {10.2172/5428704},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1982,
month = 1
}

Technical Report:

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  • Surface-micromachined silicon inertial sensors are limited to relatively high-G applications in part because of the fundamental limitations on proof mass imposed by the manufacturing technology. At the same time, traditional micromolding technologies such as LIGA do not lend themselves to integration with electronics, a capability which is equally necessary for high-performance inertial sensors. The silicon micromolding processes described in this report promise to offer both larger proof masses and integrability with on-chip electronics. In Sandia`s silicon micromolding process, the proof mass is formed using a mold which is first recessed into the substrate using a deep silicon trench etch, thenmore » lined with a sacrificial or etch-stop layer, and filled with mechanical polysilicon. Since the mold is recessed into the substrate, the whole micromechanical structure can be formed, planarized, and integrated with standard silicon microelectronic circuits before the release etch. In addition, unlike surface-micromachined parts, the thickness of the molded parts is limited by the depth of the trench etch (typically 10--50 {micro}m) rather than the thickness of deposited polysilicon (typically 2 {micro}m). The fact that the high-aspect-ratio section of the device is embedded in the substrate enables the monolithic integration of high-aspect-ratio parts with surface-micromachined mechanical parts, and, in the future, also electronics. The authors anticipate that such an integrated mold/surface micromachining/electronics process will offer versatile high-aspect-ratio micromachined structures that can be batch-fabricated and monolithically integrated into complex microelectromechanical systems including high-performance inertial sensing systems.« less
  • The prospects for the low-aspect-ratio (A) tokamak to fulfill the requirements of viable fusion power plants are considered relative to the present status in data and modeling. Desirable physics and design features for an attractive Blanket Test Facility and power reactors are estimated for low-A tokamaks based on calculations improved with the latest data from small pioneering experiments. While these experiments have confirmed some of the recent predictions for low-A, they also identify the remaining issues that require verification before reliable projections can be made for these deuterium-tritium applications. The results show that the low-A regime of small size, modestmore » field, and high current offers a path complementary to the standard and high A tokamaks in developing the full potential of fusion power.« less
  • Double shell targets may have decisive advantages over single shells for achieving a number of goals in the laser fusion program. With 0.2 ..mu.. light, such designs achieve 500 to 1000 times liquid density at 2 kJ absorbed; 10 percent or more of breakeven at 15 kJ absorbed, and gains of 10 or more at 200 kJ absorbed. These targets are relatively insensitive to preheat, laser pulse shape, and hydrodynamic instability. A double shell in which the outer pusher is fuel may achieve a gain of 1000 for lasers in the 1 to 10 megajoule size. Ultra thin targets havemore » only about a factor of two reduction in power shells with aspect ratios of 2 to 4 while requiring about the same input energy and achieving about the same gain. Their extreme sensitivity to preheat, symmetry, and hydrodynamic instability makes them unattractive for targets in advanced lasers systems.« less
  • During the reporting period of this HIT grant (1 June 1995--31 May 1997) we`ve conducted further stability analysis, used the TIP diagnostic to measure plasma fields in HIT, and developed a single-parameter helicity injector model. HIT has undergone a significant upgrade to the HIT-II configuration which is described here. Parts for HIT-II have been designed, ordered, and received under this grant and are being assembled under the subsequent grant.
  • Low Aspect Ratio is one of many design criteria for torsatrons. A new magnetic field design technique based on the Hamiltonian structure of magnetic field line flow is used to investigate feasible torsatron configurations. Significant improvements have been made in the computer code IFS. The problem of too large a magnetic axis wobble has been solved with the addition of an l = 1 m = 6 helical coil. A practical non-intersecting coil set has been designed. 4 refs., 2 figs., 1 tab.