Enhanced peak-to-valley current ratio in InGaAs∕InAlAs trench-type quantum-wire negative differential resistance field-effect transistors

Trench-type narrow InGaAs quantum-wire field-effect transistors (QWR-FETs) have been fabricated on (311)A InP V-groove substrates by hydrogen-assisted molecular-beam epitaxy. Enhanced negative differential resistance (NDR) effects with a peak-to-valley ratio (PVR) as high as 13.3 have been observed at an onset voltage of 0.16V in the QWR-FETs at 24K. The PVR increased with reductions in the InGaAs epitaxial layer thickness, which caused an enhanced mobility difference between the QWR and side quantum wells (QWs). This forms a velocity modulation transistor based on the real-space transfer of electrons from the high mobility QWR to the low mobility side QWs. The NDR effects were observed up to 230K as the gate length was decreased to 50nm. A unique feature of the QWR-FET is that NDR effects are controllable with the gate bias in a three-terminal configuration.