I have got a circuit with a mechanical relay. The mechanical relay used is a normally closed one. The problem is that I need to replace the relay with a some solid state device which behaves very much similar to this mechanical relay. That is, even when the circuit is not powered by any supply, since the mechanical relay is a normally closed one, the solid state device should act as a normally closed one. for example, consider a p channel mosfet. The mosfet is a normally closed one if Vgs=0 and when there is some Vds. In my case I need a solid state device which acts as normally closed even with no Vds and no Vgs