Observation of ion-induced changes in the channel current of high electron mobility AlGaN/GaN transistors (HEMT)

We report on the observation of channel current modulation by exposing AlGaN/GaN high electron mobility transistors (HEMT) to fluxes of ions of different signs generated by an ion spray technique. In these experiments, the gate was directly exposed to the ion flux without intermediate insulating or metallic layers. We were able to vary the channel current over several orders of magnitude in a reversible manner. The effect is likely to be caused by the compensation of bound ions at the GaN surface. Using this effect, we were able to realize a miniaturized charge-amplifying device sensitive to the sign and quantity of ion fluxes, with an amplification factor of about 1000.