Total angular momentum conservation during tunnelling through semiconductor barriers

We have investigated the electrical transport through strained p-type Si/Si1 − xGex double-barrier resonant tunnelling diodes. The confinement shift for diodes with different well width, the shift due to a central potential spike in a well, and magnetotunnelling spectroscopy demonstrate that the first two resonances are due to tunnelling through heavy-hole levels, whereas there is no sign of tunnelling through the first light-hole state. This establishes for the first time the conservation of the total angular momentum in valence band resonant tunnelling. It is also shown that conduction through light-hole states is possible in many structures due to tunnelling of carriers from bulk emitter states.