Thresholds for impact ionisation in InSb at 77K

The thresholds in energy for 5 different impact ionisation processes in InSb at 77K were calculated on the basis of a critical review of the available bandstructure data for largerk values. An accurate threshold value of 243 meV ± a few meV is given for the main process. It is shown that production of light holes by impact ionisation is highly improbable. It is suggested that double ionisation and light hole initiated ionisation may be equally important in interpreting quantum efficiency data. Impact ionisation by L-band electrons may contribute significantly to the avalanche in Gunn domains, explaining the rapid quenching of the latter.