Description: New insight into the microstructure and doping of unintentionally n-type microcrystalline silicon carbide

This title appears in the Scientific Report : 2016

New insight into the microstructure and doping of unintentionally n-type microcrystalline silicon carbide

Microcrystalline silicon carbide (μc-SiC:H) deposited by hot wire chemical vapor deposition (HWCVD) and plasma-enhanced chemical vapor deposition (PECVD) provide advantageous opto-electronic properties, making it attractive as a window layer material in silicon thin-film and silicon heterojunction s...

Personal Name(s):	Pomaska, Manuel (Corresponding author)
	Köhler, Florian / Zastrow, Uwe / Mock, Jan / Pennartz, Frank / Muthmann, Stefan / Astakhov, Oleksandr / Carius, Reinhard / Finger, Friedhelm / Ding, Kaining
Contributing Institute:	Photovoltaik; IEK-5
Published in:	Journal of applied physics, 119 (2016) 17, S. 175303
Imprint:	Melville, NY American Inst. of Physics 2016
DOI:	10.1063/1.4948479
Document Type:	Journal Article
Research Program:	Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC) Solar cells of the next generation
Link:	OpenAccess OpenAccess
	Publikationsportal JuSER

Please use the identifier: http://hdl.handle.net/2128/17100 in citations.
Please use the identifier: http://dx.doi.org/10.1063/1.4948479 in citations.

Microcrystalline silicon carbide (μc-SiC:H) deposited by hot wire chemical vapor deposition (HWCVD) and plasma-enhanced chemical vapor deposition (PECVD) provide advantageous opto-electronic properties, making it attractive as a window layer material in silicon thin-film and silicon heterojunction solar cells. However, it is still not clear which electrical transport mechanisms yield dark conductivities up to 10−3 S/cm without the active use of any doping gas and how the transport mechanisms are related to the morphology of μc-SiC:H. To investigate these open questions systematically, we investigated HWCVD and PECVD grown layers that provide a very extensive range of dark conductivity values from 10−12 S/cm to 10−3 S/cm. We found out by secondary ion mass spectrometry measurements that no direct correlation exists between oxygen or nitrogen concentrations and high dark conductivity σd, high charge carrier density n, and low activation energy Ea. Higher σd seems to rise from lower hydrogen concentrations or/and larger coherent domain sizes LSiC. On the one hand, the decrease of σd with increasing hydrogen concentration might be due to the inactivation of donors by hydrogen passivation that gives rise to decreased n. On the other hand, qualitatively consistent with the Seto model, the lower σd and lower n might be caused by smaller LSiC, since the fraction of depleted grain boundaries with higher Ea increases accordingly.