The diode of the lowest voltage

Question

Which diode (semiconductor material) has the lowest voltage in the direction of conductivity?

Answer 1

In fact, Schottky Diodes

have the lowest forward voltages. This means, that this is not a question of band gap "voltage" (this is a energy difference originally!) but of technology. Second are Germanium point contact diodes with gold wires.

"Diodes" made from Galena maybe are very low too, but due to the wiggely properties I would not dare to write about the "impressions" I had some times for some seconds on a scope.

Answer 2

EDIT
Georg's note make me see that is not an answer to the OP.
I leave the rest of the text only to make notice of a very promising new techonoly.
end EDIT

Superconducting Niobium Chip Smashes Silicon Power Consumption Standards A superconducting logic chip with a clock speed of 6 GHz beats silicon energy efficiency by two orders of magnitude

Ref: Ultra-Low-Power Superconductor Logic
Abstract:

We have developed a new superconducting digital technology, Reciprocal Quantum Logic, that uses AC power carried on a transmission line, which also serves as a clock. Using simple experiments we have demonstrated zero static power dissipation, thermally limited dynamic power dissipation, high clock stability, high operating margins and low BER. These features indicate that the technology is scalable to far more complex circuits at a significant level of integration. On the system level, Reciprocal Quantum Logic combines the high speed and low-power signal levels of Single-Flux- Quantum signals with the design methodology of CMOS, including low static power dissipation, low latency combinational logic, and efficient device count.