Mechanisms of negative resistivity and generation of terahertz radiation in a short-channel In0.53Ga0.47As/In0.52Al0.48As transistor

The effect of negative resistivity observed at anomalously low voltages in output characteristics of modulation-doped In0.53Ga0.47As/In0.52Al0.48As field-effect transistors is considered. In the discussed experiments, the threshold for appearance of negative resistivity depends not only on the gate length, which was mentioned before, but also on the gate-drain voltage. It is shown that the negative differential resistivity observed at output characteristics of the short-channel In0.53Ga0.47As/In0.52Al0.48As field-effect transistor at anomalously low threshold voltages is related to the formation of the second transport channel as a result of resonance transition of hot electrons from upper levels of the quantum well to the above-barrier layer via the states of ionized donor impurity. The results of the analysis of the low-frequency experiment are used to interpret splitting of the line of emission of the short-channel transistor in the region of terahertz frequency.