I would like to know the best method to convert gamma radiation to electrical energy. I have already considered silicon semiconductor cells so please comment or answer if u have any other answers.
A possibility would be to have a sheet of metal in the beam of gamma rays. As the gamma rays would eject some of the electron from the material, the electrons would carry most of the gamma rays momentum (some would be transferred to the atom), so would travel in approximately the same direction as the initial gamma ray. The emitted electrons could then be captured in a thicker piece of metal.
Since there is now a difference in charge between these two pieces of metal, it would be possible to use it like a battery (or other DC source). The voltage/current would be a bit irregular, so would have to be electrically "tidied" before it could be safely used for power but that is a circuit problem.
Hopefully that helps
The only practical way with reasonable efficiency is to absorb the gamma rays, turn the energy into heat, and drive a heat engine. A nuclear power plant does this with the gammas it makes, along with other radiation, using the energy to drive a steam turbine.
If moving parts are a problem, the heat engine can be a thermoelectric generator, but efficiency is much lower.