Deuteron Magnetic Resonance in a-Si and a-SiGe Produced from Fluorides
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DEUTERON MAGNETIC RESONANCE IN a-Si AND a-SiGe PRODUCED FROM FLUORIDES* V. P. Bork,t P. A. Fedders, and R. E. Norberg, Washington University, St. Louis, Missouri 63130 D. J. Leopold,$ K. D. Mackenzie, and W. Paul, Harvard University, Cambridge, Massachusetts 02138 ABSTRACT Deuteron magnetic resonance line shapes and spin lattice relaxation times are presented for a-Si:D,F and a-SiGe:D,F. These parameters differ from those for typical a-Si:D,H samples, but in some respects are similar to those for an annealed a-Si:D,H sample. The a-SiGe:D,F spectra display an unusually large broad central weakly bound D resonance component and a barely-resolved Ge-D quadrupolar doublet. Comparisons indicate substantial differences in void morphology between the a-Si:D,F and a-SiGe:D,F. INTRODUCTION Most previous deuteron magnetic resonance (DMR) studies of amorphous semiconductors have examined a-Si:D,H samples. Three principal DMR line shape components are observed: a resolved doublet from tightly bound D, a broad central line from weakly bound D, and a narrow central (NC) component associated with the molecular D2 and lHD in microvoids [1]. Each component usually is characterized by a distinct relaxation behavior. We report here the extension of such studies to amorphous semiconductors produced from fluorides. Plasma-deposited samples of a-Si:D,F and a-SiGe:D,F were prepared by rf glow discharge under the conditions given in Table I. These are device-quality materials and contain about 1 at.% F. For comparison the table also lists properties of a Xerox PARC a-Si:D,H sample previously investigated [2] and more recently sequentially-annealed [2] at various temperatures for periods of 30 minutes. Pulsed Fourier transform DMiR measurements were performed at 30.7 MHz with a Bruker CXP spectrometer. Spin lattice relaxation times T1 were obtained by the saturation-recovery method. Transverse relaxation times T2 for the narrow central component were obtained from the central line shapes. Composite pulses and quadrupole echoes provided line shapes for the full broad resonance. a-Si:D,F Figure 1 compares a 6.8 K DMR spectrum for a-Si:F,D (#325) with some 11.4 K spectra of a-Si:D,H Sample II before and after annealing. The concentration of bound D (Table I) is smaller for the sample prepared from fluorides than for typical unannealed a-Si:D,H such as Sample II. The substantial ratio of molecular deuterium to bound deuterium in a-Si:D,F (#325) is similar to the corresponding ratio in a-Si:D,H Sample IIC *Supported in part by NSF Grants 83-04473 and 85-03083 and by SERI under subcontract XB-2-02144-1 f prime contract EG-77-C-01-4042 with The Department of Energy. Xerox Corporation Pre-Doctoral Fellow 'Present Address: McDonnell Douglas Research Labs
Mat. Res. Soc. Symp. Proc. Vo4.70, 1 198b Materials Research Society
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(annealed at 450'C). Sample liE (annealed at 550°C) and the a-Si:D,F have similar NC line widths at 11 K. Both these samples have narrow central line widths significantly narrower near 20 K than those for a typical as-depo
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