Effect of Reactor Pressure on Electrical and Structural Properties of Diamond Films Grown by Hot-Filament CVD
M. Ullaha,b, E. Ahmed a and A.M. Rana a
aDepartment of Physics, Bahauddin Zakariya University, Multan-60800, Pakistan
bpresent address: Department of Physics, G.C. University Faisalabad Layyah Campus, Layyah, Pakistan
Received: March 11, 2014; In final form: March 30, 2016
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Polycrystalline diamond films with preferred (111) and (222) facets were fabricated inside hot filament chemical vapour deposition reactor on silicon wafers using a mixture of 1% methane in hydrogen at various reactor pressures ranging from 10 to 50 mbar. Regarding characterization of diamond films, internal texture, surface morphology, quality of diamond and electrical conductivity were investigated using X-ray diffraction, scanning electron microscopy, the Raman spectroscopy and four-point-probe van der Pauw techniques, respectively. Results of these studies demonstrate that polycrystalline diamond structure is grown in random orientation with (111) facet being dominant showing sharp grain boundaries. Moreover, growth rate was found to increase with pressure up to 20 mbar and then decreased for further rise in pressure. That is why grain density is high with relatively smaller grains at higher pressures caused by higher nucleation rates. In contrast, electrical resistivity decreased ≈3 orders of magnitude showing a minimum at 2.9×106 Ωcm as pressure was increased in the reactor. Reactor pressure during film growth resulted in poor surface morphology, absence of sp3 bonds and low resistivity. Hence, decrease of resistivity makes diamond films desirable for many electrical applications in semiconducting/electronic devices.

DOI: 10.12693/APhysPolA.131.1419
PACS/topics: HFCVD, electrical properties, diamond films, growth, reactor pressure