Backside-gated modulation-doped GaAs-(AlGa)As heterojunction interface

We present a new kind of gated modulation-doped GaAs-(AlGa)As heterojunction interface. The gate voltage is applied from the backside of the specimen. Gate voltage dependences of the two-dimensional electron concentration and its mobility μ are determined. The density variation is strictly linear in gate voltage, and the mobility follows approximately a law μ∝n5/2 over the explored region. This concept is similar to a junction field-effect transistor but with a two-dimensional channel. Forward bias improves the mobility by ≊50% to ≊120 000 (cm2/V sec).