Hello, I seem to be having a problem with an assignment : I need to calculate the electric field at which optical phonons will be emitted. Here's what I have been given: Semiconductor with effective mass m=0.26*m0. The optical phonon energy is 50 meV. The mean scattering time is tau=10e-13 s at 300K. There was a hint given in the assignment as well: "the total kinetic energy of an electron is the sum of hte thermal energy and the acquired energy from the field in the form of drift velocity." Can I get some guidance here? I am reviewing my notes but some help would be appreciated. Thanks in advance.