A superlattice as an undulator

The scattering length of ballistic electrons in a semiconductor may be as large as 2−3 × 10−5cm [M. Heiblum et al., Phys. Rev. Lett. 55 (1985) 2200]. This means that a semiconductor superlattice (SL) with a period of 200Åmay contain more than ten periods and its length is still smaller than the above value. tion and photon emission of electrons in a superlattice may be described as in an undulator. Therefore, there is a close analogy between ballistic electrons in a superlattice and electrons in a free electron laser (FEL). ng upon this analogy the intensity of photon emission in the IR region and the gain are calculated. It is shown that the amplification can be significant, reaching tens of %.