Field emission from semiconductors has been theoretically investigated by describing the energy transfer of electron. The authors developed a theory for the replacement process to calculate the energy exchange Delta epsilon between the electrons outgoing from and incoming to the semiconductor cathode. The obtained Delta epsilon is found to increase with increasing T and decreasing field F but to be almost independent of doping. It is also found that Delta epsilon is always positive, implying the cooling effect of field emission from the semiconductors for all temperatures. (c) 2008 American Vacuum Society.