FIELD-EFFECT TRANSISTOR STRUCTURE BASED ON STRAIN-INDUCED POLARIZATION CHARGES

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.