Suspended quantum point contact with triple channel selectively driven by side gates

Abstract

The experimental study of the suspended GaAs quantum point contact (QPC) equipped with in-plane side gates reveals that, under such conditions, the QPC constriction has an unusual triple-channel structure involving three conductive channels with the quantized conductance selectively driven by the gates. The analysis of capacitance coefficients and channel widths allows us to conclude that the channels are narrow, compared to the lithographic constriction of the QPC, and that two of the channels are located along the constriction edges, while the other one passes along the middle line. The suspended QPC with the selectively driven triple-channel structure represents a device with an enhanced functionality. The electrostatic mechanism of the channel formation, specific for trench-type suspended QPCs with side gates, is discussed.

Suspended semiconductor nanostructures: physics and technology

“…As noted above, a significant difference between trench-etched from gate-defined QPCs is the ability to apply sufficiently large voltage differences between the side gates ΔV G . The study of conductance in suspended trench-etched GaAs-based QPC at sufficiently large ΔV G in addition to observation of lateral-electric-field-induced spin polarization [52] revealed an unusual multichannel transport mode in a single QPC [53]. Conductive channels, as will be shown below, are formed along the lithographic trenches.…”

“…It was previously shown that applying a voltage difference between the side gates allows the creation of lateral electric fields sufficient to induce spin polarization in both InAs [46] and GaAs [52] based QPCs due to the LSOC effect. Another advantage of trench-type structures is that they allow independent application of the gate voltage, and hence the study of conductance as a function of two independent gate voltages [53,54]. Such measurements reveal an unusual multichannel electron transport characterized by quantised conductance of individual channels within a single QPC [53][54][55].…”

“…Another advantage of trench-type structures is that they allow independent application of the gate voltage, and hence the study of conductance as a function of two independent gate voltages [53,54]. Such measurements reveal an unusual multichannel electron transport characterized by quantised conductance of individual channels within a single QPC [53][54][55]. Moreover, the channels can function independent of each other and demonstrate the effects of interaction between them.…”

“…In recent studies on the conductance of GaAs single trenchtype QPCs both suspended [53,54] and non-suspended [55], double-and triple-channel electron transport was experimentally observed. In this case, the conductance of individual channels is quantized and independently controlled by lateral in-plane gates, both at a small and a large number of populated 1D subbands.…”

Двухканальный Электронный Транспорт В Подвешенных Квантовых Точечных Контактах С Боковыми Затворами

“…Изучение электронного транспорта в одиночных КТК с боковыми затворами, отделенными от микросужения с помощью литографических траншей, показало, что вблизи краев микросужения, вдоль литографических траншей, могут формироваться дополнительные проводящие каналы [5,6]. Природа их возникновения до конца не ясна и, по-видимому, заключается в специфических электростатических условиях, реализующихся в КТК в результате вытравливания траншей.…”