鄰近束縛能態對類一維窄通道電性傳輸的影響

Abstract

本論文探討由分離閘極技術局域形成束縛能態對鄰近類一維窄通道電性傳輸的影響。我們利用電子束微影製程技術在高遷移率的GaAs/AlGaAs異質結構二維電子氣樣品上製作數對相鄰的獨立金屬閘極，藉由外加偏壓於金屬閘極產生位障，進而限制載子於二維電子氣的運動路徑形成低維度系統，在低溫下分別獨立控制兩相鄰窄通道的通道寬度，觀察鄰近束縛能態對類一維窄通道電性傳輸的影響。 我們藉由金屬閘極的安排，改變數種束縛能態與類一維窄通道的間距，換置不同的類一維窄通道以及控制數種通道寬度後，並沒有發現由鄰近束縛能態對類一維窄通道電性傳輸造成的明顯影響，不同於Bird團隊的實驗觀察，由鄰近束縛能態造成類一維窄通道的電導值發生振盪峰值；進一步分析鄰近閘極的存在造成類一維窄通道的電性傳輸變化，卻發現鄰近金屬閘極所產生的位障會影響到窄通道，使得窄通道在特定偏壓位置發生電導值些微下降的現象。

We have investigated the influence of nearby bound state on electrical transport of a quasi-one dimensional narrow channel defined by split-gate technique at 1.7K. Pairs of isolated metal split gates on a high mobility GaAs/AlGaAs heterostructure were made by electron-beam lithography. By individually biasing split gates coupled quasi-one dimensional narrow channels can be created and the electrical transport arises from the interactions between them is studied. A special arrangement of six metal gates is chosen that there are numerous configurations with different distances between bound state and the quasi-one dimensional narrow channel. As a result, there is no significant change of the channel's conductance in the presence of nearby bound state, insensitive to the channel's width and the distance between the bound state and the narrow channel (NC). Meanwhile, it is quite different from the observation of Bird group. that a resonant conductance of detector NC appears due to the interaction between bound state and a quasi-one dimensional NC. Furthermore, we analyzed the influence of nearby biased metal gate on electrical transport of a quasi-one dimensional NC. We found that the potential of biased nearby metal gate would further influence the NC resulting in the slight decrease of NC conductance at a certain gate voltage.