量子点晶体管的研究与制备

论文总字数：31830字

摘 要

晶体管是电子学的基础型器件，应用于各种类型的电子器件中。相比于无机晶体作为有源层的传统型晶体管器件（硅CMOS），量子点作为有源层制备的量子点晶体管器件具有一些独特的优势，如在制备工艺方面，可采用旋涂法加工包括量子点层在内的基板衬底，其成本远比传统晶体的外延生长法低的多；同时，晶体管尺寸缩小至纳米尺度时会产生许多如量子效应在内的新现象，指导未来新器件利用量子点纳米材料的低维特征与晶体管尺度特征相对应，以获得最佳的器件性能。

然而，由于量子点受本身载流子运输机制的限制，量子点晶体管器件的载流子迁移率最高值约30 cm²V^-1S^-1，远达不到传统晶体管器件（10³cm² V^-1 S^-1）。为了提升其载流子的迁移率，本文研究并制备了量子点场效应晶体管器件，并对其材料的生长条件和制备工艺进行探索，取得了如下的实验结果：

1、稳定量子点的材料制备

首先，根据量子点合成奥斯瓦尔德熟化原理，使用纯度为99%的硒粉（Se）作为硒源，氧化镉（CdO）作为镉源，油酸(OA)作为长链配体，通过过热注入法合成了较为稳定的CdZnSeS量子点，经过测量其吸收光谱与发射光谱，以及使用高分辨率透射电镜进行观察，得到其粒径大小为6.7 nm，荧光量子产率为33%。

2、量子点场效应晶体管的设计和制备

使用ITO涂层玻璃作为基板，合成出的CdZnSeS量子点作为有源层，SU-8作为绝缘层，Al作为栅端电极的结构，制备场效应晶体管器件。经过半导体分析仪测试其输出曲线与转移曲线。得到不同环境下器件的载流子迁移率。

3、量子点场效应晶体管器件迁移率提升的参数和条件

在使用CdZnSeS量子点进行有源层旋涂制备薄膜时，我们使用了TBAI-甲醇溶液对量子点进行了配体置换。并通过设定不同的旋转速度，对绝缘层以及量子点有源层的厚度进行了调整和控制，得到最佳厚度的绝缘层和量子点层器件。最终发现，采用365 nm的紫外光灯长波段进行照射激发，在配体置换后，绝缘层最佳厚度为510 nm，量子点膜厚为40 nm, 器件载流子迁移率最大值达到4.1×10^-5 cm² V^-1 S^-1。

关键词：CdZnSeS量子点；配体置换；场效应晶体管

Abstract

Transistors are the basic devices for electronics and are used in various types of electronic devices. Compared to a conventional transistor device (silicon CMOS) in which an inorganic crystal is used as an active layer, a quantum dot transistor device in which a quantum dot is prepared as an active layer has some unique advantages. For example, in the manufacturing process, a spin coating method can be used to process. The cost of which is much lower than the cost of conventional crystals. At the same time, when transistors are reduced to the nanoscale, many new phenomena such as quantum effects are generated, guiding the use of new devices in the future. The low-dimensional features of quantum dot nanomaterials correspond to the scale characteristics of the transistor to achieve the best device performance.

However, due to the limitation of the quantum dots by their own carrier transport mechanism, the highest carrier mobility of quantum dot transistor devices is about 30 cm²V^-1S^-1, which is far from the traditional transistor devices (10³cm² V^-1 S^-1). In order to improve the carrier mobility, the quantum dot field effect transistor device was studied and fabricated in this paper.

1. Preparation of materials for stable quantum dots

First, according to the quantum dot synthesis Oswald ripening principle, selenium powder (Se) with the purity of 99% is used as a selenium source, cadmium oxide (CdO) is used as a cadmium source, and oleic acid (OA) is used as a long-chain ligand, through overheating. The stable CdZnSeS quantum dots were synthesized by injection method. The absorption and emission spectra of the CdZnSeS quantum dots were measured. High-resolution transmission electron microscopy was used to observe the diameters of the particles. The particle size was 6.7 nm and the fluorescence quantum yield was 33%.
2. Design and preparation of quantum dot field effect transistors
Using an ITO-coated glass as a substrate, a CdZnSeS quantum dot was synthesized as an active layer, SU-8 was used as an insulating layer, and Al was used as a gate electrode structure to fabricate a field effect transistor device. After the semiconductor analyzer test its output curve and transfer curve. The carrier mobility in different environments was obtained.
3. Parameters and conditions for improving the mobility of quantum dot field effect transistor devices
When using CdZnSeS quantum dots for spin coating the active layer to prepare thin films, we used ligand replacement with TBAI-methanol solution. By setting different rotation speeds, the thicknesses of the insulating layer and the quantum dot active layer are adjusted and controlled to obtain the optimal thickness of the insulating layer and the quantum dot layer device. Eventually, it was discovered that the 365 nm UV lamp was used to irradiate the long wavelength band. After ligand replacement, the optimal thickness of the insulating layer was 510 nm, the quantum dot film thickness was 40 nm, and the maximum carrier mobility was 4.1×10^-5 cm² V^-1 S^-1.

KEY WORDS: CdZnSeS quantum dots; ligand replacement; field effect transistors

目 录

摘要 I

Abstract III

目 录 V

第一章 绪论 1

1.1 研究背景 1

1.2 量子点场效应晶体管材料的国内外研究现状 1

1.3 论文研究内容及意义 3

1.4 论文组织结构 3

第二章 场效应晶体管基础理论 5

2.1 场效应晶体管概念 5

2.2 场效应晶体管特征 5

2.2.1 场效应晶体管结构 5

2.2.2 场效应晶体管原理 6

2.2.3 场效应晶体管特性曲线 6

2.2.4 场效应晶体管性能表征 8

2.3 本章小结 9

第三章 CdZnSeS量子点合成与表征 11

3.1 量子点基础理论 11

3.1.1 量子点概念 11

3.1.2 量子点特性 11

3.2 量子点合成方法 11

3.2.1 应变自组装法 11

3.2.2 离子注入法 12

3.2.3 胶体合成法 12

3.3 量子点优化方法 13

3.4 本论文CdZnSeS量子点合成实验 15

3.4.1 实验药品 15

3.4.2 实验过程 15

3.5 CdZnSeS量子点表征 16

3.5.1 紫外-可见分光光度计表征与量子尺寸的计算 16

3.5.2 荧光分光光度计表征与荧光量子产率的计算 17

3.6 本章小结 18

第四章 基于CdZnSeS量子点场效应晶体管的制备与表征 19

4.1 器件结构 19

4.2 器件制备过程 19

4.2.1 基板的准备与清洗 19

4.2.2 有源层的制备与配体置换 20

4.2.3 绝缘层的制备 20

剩余内容已隐藏，请支付后下载全文，论文总字数：31830字