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Study of electronic states in 10nm-scale semiconductor quantum dots and exploration of their memory functions

10nm级半导体量子点电子态研究及其记忆功能探索

基本信息

批准号：
09450136
负责人：
SAKAKI Hiroyuki
金额：
$ 5.82万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09450136/
关键词：
10nm InAs quantum dot Self-assembly Inverted HEMT structure Memory function Optical detector Quantum point contact Resonant tunnel structure Capacitance-voltage spectroscopy 自己形成量子箱 FET 量子化コンダクタンスヒステリシス特性 InAs量子箱逆HEMT 電子状態

项目摘要

Semiconductors (e.g., InAs) deposited on a lattice-mismatched substrate (e.g., GaAs) yields 10 nm-scale Quantum dots (QDs) spontaneously. We have exploited them to make memory devices, in which the presence and absence of a single electron in InAs QDs correspond to "1" and "0". We have also investigated electronic properties of such QDs.First, we prepared an inverted high electron mobility transistors (HEMT), in which InAs QDs are embedded between the surface gate electrode and a two dimensional electron channel at the GaAs/n-AlGaAs heterojunction. By applying gate voltage (Vg) over 0.9 V, the threshold voltage of the transistor shifted to the positive side by DELTAV, resulting from the supply of electrons from the channel to QDs. This proves the feasibility of new memory effect. Analytical studies of transport characteristics have shown that each QD stores one electron each, since the Coulombic repulsion originating from the first trapped electron prevents the trapping of second electron. If the second electron is stored in the QD, it easily tunnels out from the QD.In addition, we studied the "write" and "erase" (i.e., charge and discharge) processes controlled by the light illumination. Further, we prepared and studied a prototype device of a quantum point contact, in which the charge trapping in QDs near the point contact leads to a clear hysteresis characteristics in the quantized conductance.We have studied electronic levels of InAs QDs in AlGaAs layer by photoluminescence and capacitance-voltage spectroscopy. The quantized state in QDs was found to increase by ^- 200 meV when the Al content in AlGaAs barrier layer is raised. We clarified also the shape of wavefunctions of electrons confined in QDs by magneto-tunneling spectroscopy.

半导体（例如，InAs）沉积在晶格失配的衬底（例如，GaAs）自发地产生10 nm尺度的量子点（QD）。我们已经利用它们来制造存储器件，其中InAs量子点中单个电子的存在和不存在对应于“1”和“0”。首先，我们制备了一个倒置的高电子迁移率晶体管（HEMT），其中InAs量子点嵌入在GaAs/n-AlGaAs异质结的表面栅电极和二维电子沟道之间。通过施加超过0.9V的栅极电压（Vg），晶体管的阈值电压向正侧偏移Δ V，这是由于电子从沟道供应到QD。这证明了新记忆效应的可行性。输运特性的分析研究表明，每个QD各自存储一个电子，因为源自第一个被捕获电子的库仑排斥阻止了第二个电子的捕获。如果第二个电子存储在QD中，则它很容易从QD中隧穿出来。此外，我们研究了“写入”和“擦除”（即，充电和放电）过程。此外，我们制备并研究了量子点接触的原型器件，量子点接触附近的量子点中的电荷陷阱导致量子化电导具有明显的滞后特性。我们利用光致发光和电容-电压谱研究了AlGaAs层中InAs量子点的电子能级。发现当AlGaAs势垒层中Al含量增加时，量子点的量子化态增加了^- 200 meV。我们还澄清了磁隧道谱的量子点中的电子被限制的波函数的形状。