Device-grade hydrogenated amorphous silicon produced by dc magnetron reactive sputtering

Technical Report · Mon Oct 01 00:00:00 EDT 1990

OSTI ID:6436407

Abelson, J R ^[1]

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1. Illinois Univ., Urbana, IL (USA)

The goal of this project is to determine the fundamental growth mechanisms of hydrogenated amorphous silicon (a-Si:H) and related alloys. This is important because thin films of these materials must have the high quality and stability required for 15%-efficient solar cells and be produced at high rates and low cost over large areas: achieving these requirements is more likely if the physics and chemistry governing film growth are understood. The complexity of growing the amorphous silicon-germanium allows layers needed for the low-bandgap portion of a tandem solar cell underscores the problem: Empirically optimizing this intricate process is not likely to succeed. This project proceeds in two stages: (1) produce state-of-the-art a Si:H using remote-source deposition methods, such as magnetron sputtering and remote-plasma glow discharge; and (2) analyze film growth kinetics using in-situ diagnostics, such as mass spectrometry, infrared adsorption spectroscopy, and spectroscopic ellipsometry. In the future this work will also encompass silicon-based alloys and serve to guide alloy optimization. This report details progress during the first project stage, in which we deposited device-grade a-Si:H using dc-magnetron reactive sputtering. We grew a-Si:H think films with 10--40 atom percent hydrogen, and determined their electronic properties and hydrogen bonding modes. Films containing up to 28 percent hydrogen were similar to state-of-the-art glow-discharge produced material suitable for solar cells. A key indicator of the material electronic quality is the mobility-recombination-lifetime product; we measured values for the minority-carrier holes as high as 1 {times} 10{sup {minus}8} cm{sup 2}/V, and for majority-carrier electrons up to 2 {times} 10{sup {minus}7} cm{sup 2}/V. 75 refs., 39 figs., 3 tabs.

• Research Organization: Electric Power Research Inst., Palo Alto, CA (USA); Illinois Univ., Urbana, IL (USA)
• Sponsoring Organization: EPRI
• OSTI ID: 6436407
• Report Number(s): EPRI-GS-7012
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
14 SOLAR ENERGY
SILICON SOLAR CELLS
SYNTHESIS
AMORPHOUS STATE
DEPOSITION
GERMANIUM ALLOYS
HYDROGENATION
MATERIALS TESTING
SILICON ALLOYS
SPUTTERING
THIN FILMS
ALLOYS
CHEMICAL REACTIONS
DIRECT ENERGY CONVERTERS
EQUIPMENT
FILMS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SOLAR CELLS
SOLAR EQUIPMENT
TESTING
360601* - Other Materials- Preparation & Manufacture
140501 - Solar Energy Conversion- Photovoltaic Conversion
360603 - Materials- Properties