Germanium quantum-dot single-hole transistors with self-aligned electrodes based on a bottom-gate technology

• Main Authors: Shao-hua Hsu, 徐紹華
• Other Authors: Pei-Wen Li
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/ux7e4n

碩士 === 國立中央大學 === 電機工程研究所 === 96 === As CMOS technology is scaling into nanometer regime, the development of devices is towards small dimension, high speed, and low power consumption. Since single-electron (SE) device not only provide the aforementioned advantages but also could be applied to memory-devices, logic-devices and quantum information, the SE device has attracted lots of attention. In addition to forming a nano-scaled quantum dot (QD), it is also imperative for SE devices to form self-aligned gate and source/drain electrodes in order to manipulate the QD effectively and to suppress the gate-induced tunneling barrier lowering effect. However, the formation of SE devices from Silicon-on-Insulator(SOI) or SiGe-on-Insulator(SGOI) structures is usually with high cost and restricted design freedom. This motivates us to develop a simple method, “Selectivity oxidation of polycrystalline-SiGe” to form Ge QDs. It is a cost effective and CMOS compatible approach. The main theme of this thesis is to suppress the large incubation time for poly-SiGe deposition onto silicon dioxide (SiO2) and to form uniform poly-SiGe thin film on amorphous-Si and silicon-nitride (Si3N4) surface. In addition, we make use of the selective oxidation of the poly-SiGe thin film to form uniformly distributed Ge QDs. Then we fabricate Ge-QD single-hole transistor (SHT) based on a bottom-gate technology. We have experimentally studied the electrical characteristics and photo-effect of the Ge-QD SHT. Clear Coulomb-blockade oscillation was observed at room temperature and the gate-induced tunneling barrier lowering effect is suppressed. Furthermore, enhanced Coulomb oscillation and peak-to-valley current ratio were realized under photo-excitation. Finally, we discussed the asymmetrical features and trap assisted carrier tunneling effect of this device.