ELFT HÍRADÓ

[Kádár György <kadargy AT mfa.kfki.hu>]

MFA Szeminárium

Cesare FRIGERI (IMEM, Parma):
Stuctural Instability of Hydrogenated
a-Si/a-Ge Multilayers Prepared by Sputtering

2009. június 24.-én, szerdán, 11:00 órakor
az MTA Műszaki Fizikai és Anyagtudományi
Kutatóintézet Tanácstermében,
KFKI 26. épület I. emelet

Abstract: Amorphous SiGe:H is now the material of choice as the low band 
gap absorber in multi-junction solar cells in combination with a-Si:H. 
It has the great advantage of a higher degree of freedom as regards the 
choice of the band gap as the latter one can be tailored over some range 
by changing the Si/Ge ratio. The a-SiGe alloy can be realized from a 
sequence of thin a-Si and a-Ge layers by intermixing them by heat 
treatments.
A critical issue of hydrogenated a-SiGe:H is its instability against 
thermal annealing. The lecture will present results about the structural 
changes induced by heat treatments in hydrogenated a-Si/a-Ge multilayers 
(MLs) prepared by sputtering. Whilst the not-hydrogenated MLs do not 
undergo any structural change upon annealing, the hydrogenated ones 
exhibit remarkable surface and bulk structural degradation which 
increases with increasing H content and/or annealing temperature and 
time. This is due to the formation of hydrogen bubbles in the bulk of 
the MLs by the gathering together of H2 molecules. The formation of the 
latter ones is made possible by the release of H from the its bonds to 
Si and Ge caused by the energy supplied by the heat treatment.

Minden érdeklődőt szívesen várunk

Kádár György (MFA)
kadargy AT mfa.kfki.hu