SUPERCONDUCTING TRANSISTORS USING INAS-INSERTED-CHANNEL INALAS INGAASINVERTED HEMTS/

A newly fabricated Josephson field effect transistor (JOFET) is couple d with a two-dimensional electron gas (2DEG) in a strained InAs quantu m well inserted into an In0.52Al0.48As/In(0.53)Ga(0.47)AS inverted mod ulation-doped structure with an HEMT-type gate. We indicate the improv ed characteristics of the JOFET with the HEMT-type gate, instead of th e MIS-type gate. The superconducting critical current l(c) as well as the junction's normal resistance R(N) can be completely controlled via a gate voltage of about -1 V; this provides voltage gain over unity, the first time for a JOFET.