Field-effect transistor structure based on strain-induced polarization charges

Abstract

We suggest a new field‐effect transistor structure based on strain‐induced polarization charges. The structure utilizes the pseudomorphic growth of a barrier layer on a substrate oriented in a polar direction (i.e., 〈111〉, 〈211〉, ...). Polarization charges in the large band‐gap material are generated by the piezoelectric effect. A two‐dimensional electron gas, whose density can be modulated by an external bias, forms at the heterointerface to screen the polarization charges. Zero‐bias densities of several times 10¹¹ e/cm⁻² and turn‐off threshold voltages of 0.5 V can be achieved in the (Ga,In)As‐(Al,In)As model system. Both normally‐on and normally‐off structures are possible.