Hydrogen Diffusion and Microstructure in Undoped and Boron-dope Hydrogenated Amorphous Silicon: An IR and SIMS Study [Thesis]

Technical Report · Mon Mar 11 23:00:00 EST 1991

DOI:https://doi.org/10.2172/6095766· OSTI ID:6095766

Mitra, Saibal ^[1]

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1. Ames Laboratory (AMES), Ames, IA (United States); Iowa State Univ., Ames, IA (United States)

Hydrogenated amorphous silicon (a-Si:H) prepared by rf sputtering of a polycrystalline Si target at various rf powers 50 ≤ P ≤ 550 W (0.27--2.97 W/cm²), target to substrate distance 1 ≤ d ≤ 2", and varying hydrogen partial pressures. Doping was accomplished by introducing diborane (B₂H₆) in the plasma. Hydrogen diffusion was studied from the depth profiles obtained from the SIMS on multilayered a-Si:H/a-Si:(H,D)/a-Si:H samples. The properties of the samples were characterized by IR absorption, optical gap measurements and ESR. IR yielded quantitative and qualitative information total hydrogen content and the nature of the hydrogen bonding, respectively. Hence the hydrogen microstructure of the samples could be varied in a systematic manner and monitored from the hydrogen vibrational modes. The ESR gave information on the number of paramagnetic defects per unit volume in the samples. The IR absorption of both as-deposited and annealed samples were closely monitored and the results clearly demonstrate a strong correlation between hydrogen diffusion and its microstructure. It is shown that microvoids in a-Si:H play a critical role in the process of diffusion by inducing deep hydrogen trapping sites that render them immobile. Consequently, as the microvoid density increases beyond a critical density hydrogen diffusion is totally quenched. The diffusion results are discussed both in the context of multiple trapping transport of hydrogen in an exponential distribution of trapping sites and the floating bond model.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6095766
• Report Number(s): IS-T--1506; ON: DE91009867
• Country of Publication: United States
• Language: English

Related Subjects

656002* -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
AMORPHOUS STATE
BORON
CHEMICAL REACTIONS
CRYSTAL DOPING
CRYSTAL STRUCTURE
DIFFUSION
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
ELEMENTS
HYDROGEN
HYDROGENATION
INFRARED RADIATION
MAGNETIC RESONANCE
MASS SPECTROSCOPY
MATERIALS
MICROSTRUCTURE
MOTION
NONMETALS
RADIATIONS
RESONANCE
SEMICONDUCTOR MATERIALS
SEMIMETALS
SILICON
SPECTROSCOPY
SPUTTERING