News Article
Scientists At Princeton University Are Proposing Direct Imprint Of
Scientists at Princeton University are proposing direct imprint of
nanostructures in silicon as an alternative to photolithography and etch
(Nature, June 20, 2002). The team calls its new technique laser assisted
direct imprint (LADI). An excimer laser pulse (308nm, 20ns) melts a thin
surface layer of the silicon and a quartz mould is embossed into the
resulting liquid. Structures with a 10nm resolution have been created. The
embossing time is less than 250ns.
Professor Stuart Irvine of the University of Wales (Bangor) hopes to improve
the performance of cadmium teluride (CdTe) photovoltaic (PV) cells by
improving the ohmic contact to metal leads. A conventional cell has an
n-type cadmium sulphide layer on the front side of the p-type CdTe, forming
a junction where the photovoltage is produced. The metal contact is not a
problem for the CdS, since it is n-type, but a CdTe-metal contact is highly
resistive.
Irvine's plan - for which he has a UK ESPRC research grant - is to add a
second layer of CdS under the CdTe to make the second metal contact. This
would normally produce a resistive reverse-biased junction, but Irvine plans
to reduce the resistivity by making this a tunnel junction. This requires
high doping of both the CdTe and the second CdS layer. This is possible
using MOCVD.
the performance of cadmium teluride (CdTe) photovoltaic (PV) cells by
improving the ohmic contact to metal leads. A conventional cell has an
n-type cadmium sulphide layer on the front side of the p-type CdTe, forming
a junction where the photovoltage is produced. The metal contact is not a
problem for the CdS, since it is n-type, but a CdTe-metal contact is highly
resistive.
Irvine's plan - for which he has a UK ESPRC research grant - is to add a
second layer of CdS under the CdTe to make the second metal contact. This
would normally produce a resistive reverse-biased junction, but Irvine plans
to reduce the resistivity by making this a tunnel junction. This requires
high doping of both the CdTe and the second CdS layer. This is possible
using MOCVD.