Germanium QD Single Hole Transistor with self-aligned electrodes – device fabrication and physics study
| Autor: | Gwong-Liang Chen, 陳光亮 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 The main purpose of this thesis is to solve the shortages of single electron/hole transistors previously fabricated in our laboratory. To improve the yield and electrical characteristics of these devices, we can get the chance to understand the quantum confinement effect in detail. First, we incorporated high concentration dopants into poly-silicon layer using ion implantation. Theses dopants will diffuse to adjacent SiO2 barrier during the subsequent oxidation process, which is used to generate a single Ge QD, to form the self-aligned source/drain electrodes to the QD. This method can avoid the misalignment issues resulting from ion implantation process after gate electrode definition. Such as the asymmetrical source/drain electrodes because of the misalignment for electron beam lithography (EBL) resulting in the non-ideal effect of parasitic MOSFET. We have successfully fabricated the high temperature Ge quantum-point-contact SETs/SHTs with self-aligned source/drain electrodes using EBL and Si3N4/Si high selectivity plasma etching technology. The key process for Ge-QD SHTs with self-aligned electrodes includes the formation of Ge QD (one Ge QD smaller than 10 nm embedded in channel after fully oxidizing the SiGe nanowire), high etching selectivity between Si3N4 to Si and SiO2 to Si, EBL patterning, and device integration. The fabricated Ge-QD SHTs display homogeneous current oscillations at room temperature owing to Coulomb blockade effect. In particular, peak-to-valley current ratio is up to 500, and the background current (as low as 10-12 A - 10-13 A) doesn’t increase with applied gate voltage. This indicated that gate-induced tunneling barrier lowering is significantly suppressed owing to the self-aligned process. This thesis successfully improve the Ion/Ioff、switching speed and power consumption. Besides, we have experimentally studied the carrier quantum transport through the Ge QD using asymmetrical tunneling barriers device. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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