Do molten semiconductors conduct electricity better than solid semiconductors? I read that electrical conductivity goes up as semiconductors rise in temperature as opposed to metals that lose electrical conductivity as temperature rises. Would semiconductors continue to conduct better as they move into thier liquid state?
 A: Both silicon and germanium are four-fold coordinated diamond cubic solids as semiconductors. Upon melting the become 8- to 12-fold coordinated metallic liquids, with a conductivity at least 30x that of the semiconductor at the melt point. The coordination number increases with temperature above the melt. The classic reference for the conductivities is V. M. Glaznov et al., "Liquid Semiconductors", Plenum, New York (1969).
This large change in resistivity upon melting was used to good effect in transient conductivity measurements to get at the interface velocity response function for pulsed laser melted silicon and germanium. See, for example, Measurement of the Velocity of the Crystal-Liquid Interface in Pulsed Laser Annealing of Si, G. J. Galvin et al., Phys Rev Lett 48 33-36 (1982).
I make no claims for other semiconductors. Note that compounds like GaAs tend to lose stoichiometry before actually melting, so one would have to be careful about the conditions in any experiment you look at. 
A: The conductivity behaviour depends on the semiconductor material that is being melted.In case of silicon and germanium electrical conductivity rises exponentially and becomes equal to that of a metal.The selenium-rich alloys, however, exhibit the opposite behaviour their electrical conductivity decreases.
A: For Silicium this seems to be the case. Have a look at Figure 1 of
http://thermophysics.ru/pdf_doc/p781.pdf.
Clearly, the conductivity jumps when the Silicium becomes liquid.
Actually this is because both thermal and electric conductivity have to do with the mobility of electrons. In a metal the electrons are in a state which is known as Fermi-Gas. You can think of it as all the electrons being able to move freely in the whole solid. This means that they can exchange kinetic energy and electronic charge well and hence the high heat/electrical conductivity. When the metal becomes liquid, the electrons are bound to their atoms and which actually decreases their mobility to the speed of the atom.
Now in the case of the Semiconductors it is actually a bit more normal. Although the semiconductor has a crystalline structure like metal each electron is bound to it's atom. This means that kinetic energy is mainly transported by oscillations of the crystal lattice. Also, current is transported by freeing electrons from their atoms and recombining them somewhere else. When the semiconductor melts, this becomes easier as more thermal energy is accessible and atoms move freely as opposed to the solid case. This means that the atoms have more kinetic energy and in turn random collisions of atoms can release electrons more easily, which in turn equates to higher thermal and electrical conductivity.
