R & D
Nano Device
Emerging Device
Achievements
(一) Silicon nano thin-film optoelectronic devices:
We have invented a highly cost-effective silicon thin-film nano technology based on growing quantum dot super lattice materials on a nano-porous silica template. By controlling the chemical properties of its high surface area interface, we constructed an all-new interface binding modification optoelectronic/electronic material. Applying this high-density silicon quantum dot superlattice material to metal oxide field-effect transistors (MOSFET) successfully increased near infrared optoelectronic response. Using the gain- response mechanism of the transistor, optoelectronic response of up to 2.8A/W was measured in the 1.55μm optical communications wavelength. By modifying the size of the injected quantum dots, this nonporous silica composite material containing self-assembling silicon quantum dots can achieve outstanding ferroelectric properties. We have also successfully developed the world's first MOSFET with silicon-based ferroelectric memory functionality.
The quantum dot super lattice material and device we developed have several world-leading features:
  1. Quantum dot density and even distribution is the best in the world. The method of fabrication is also the fastest and simplest. The process temperature is very low as well;
  2. The invented silicon quantum dot superlattice structure has the simplest composition. It is essentially made up of silicon and oxygen, making it fully compatible with the silicon semiconductor industry;
  3. First to use the same nano silicon-based optoelectronic material to realize a basic optoelectronic device with broadband, high optical response, ferroelectric memory functionality and high efficiency. This represents a major contribution to the high-efficiency thin-film PV cell and non- volatile memory industries worth billions or even tens of billions of USD.



(二) Novel nano-optics and 3D crystals:
For our research into novel nano-optics and 3D crystals, we have completed research into the microwave and optical fabrication and applied research for dielectric materials, establishing the research foundation for left-handed substances. This was extended into the nano-optics field and research commenced on 3D metal crystals. Starting with fabrication of the first-layer copper metals, we have so far completed the fabrication of 4 layers of copper and titanium metal crystal at 200nm scale. A quasi 5-layered structure has also been completed.
In novel optics, we demonstrated the application of meta-materials such as left-handed substances in the optical field. A type of double-layered structure material with negative refraction that generates resonance at low grazing angle and vertical incidence angels has also been designed and simulated. We have completed research into the fabrication of metallic 2D left-handed meta- materials below the 200nm scale, and explored the behavior of splitting ring patterns from different openings with various polarized incident rays. Using an extension of copper plating technology, we can transfer copper patterns on pre-etched sub-micron nickel patterns. We discovered that the Cu-Ni-Cu-SiO2, Cu-SiO2-Cu and Cu-Cu periodic arrays presented periodic changes in the near- infrared range, and depending on the plating time, exhibit different levels of hydrophobic and hydrophilic properties. This can be applied to copper plating processes service as well as bandpass filter and hydrophobic device applications.
Future efforts will focus on the fabrication of copper crystals with wire-width under 100nm. The goal is to complete the NDL's minimum wire-width multi- layer metal technology and capabilities, and achieve integration with the metal wiring being developed for 15nm devices. At the same time, the Distributed Bragg Reflector (DBR) and optical grating will be combined to carry out research and fabrication of anti-reflective films on the front of the back electrodes of PV cells. This will increase photon reflection and serve as a photon confining design. This will increase the absorption effectiveness of sunlight and cells, and in turn, enhance efficiency.


Photo 2. Scanning electron microscope observation of the copper rod in the inclined, upper and cross-sectional views of 3D copper photonic crystals.The reflected spectra of the 3D copper photonic crystal versus various metal layers under grazing angle incidence.

(三) The third Generation thin-film PV technology
A revolutionary breakthrough in PV technology is essential if the goal of producing a total of 4TW in PV products with a module unit price below 0.3%/Wp by 2030 is to be realized. The development of low-cost, high- efficiency silicon-based nano PV module technology is aimed at achieving a conversion efficiency of at least 15%. Core research topics include:
  1. SixGe1-x-Si-SiyC1-y-ymulti-band-gap PV thin-films that can effectively absorb a broad spectrum of sunlight and provide photo-generated carrier separation. 多能隙介面光伏特薄膜。
  2. Silicon quantum dots that can increase the photo response of devices from the UV to near-IR spectrum.
  3. Super high surface area SiNWs material that can provide excellent reflectivity, wider light absorption region and adjustable band-gap for advanced PV applications.
Using a graded band-gap thin-film system SixGe1-x-Si-SiyC1-ycan effectively enhance the efficiency of PV devices absorbing broad spectrum of sunlight. Single-contact non-crystalline PV cells made used high-density plasma technology have now achieved an efficiency of 7.4%. Thin-film technology with such a low thermal budget and high-deposition rate opens up the possibility of high-efficiency, multi-junction SiGeC PV cells. Man-made novel photonic materials and nc-Si/Ms self-assemble composites can increase the PV effectiveness by using the charge resonant transportation within nano thon film through Schottky-like rectified nano particles and the metal interface.
For nano wire materials, super high surface area, low reflectivity, wide spectrum light absorption and adjustable bandgap nano light wires have been demonstrated. The theoretical nano light wire efficiency is as high as 16%, but to date, the silicon nanowire PV conversion efficiency in the literature is still quite low. The development of the novel silicon nanowire thin-film will therefore become the main contributor to more efficient PV cells. The silicon nanowire PV cell prototype's surface has excellent anti-reflection properties with a super-low reflectivity of below 0.08% for wavelengths between 200 - 1100nm. These nano technologies open the possibility of developing the 3rd generation silicon-based high-efficiency (20%) PV cells. At the top of the development list is silicon nanowire thin-film PV cells and super anti- reflective, high-efficiency blended silicon nano particle organic thin-film PV. At the same time, we have also developed large area (100cm2) organic PV modules based on spin coating on glass and flexible plastic substrates.



(四) Future Planning:
To prevent catastrophic climate change due to economic growth, non-carbon technologies should be used to as the primary energy supply. Unfortunately, existing PV technology is still too expensive to compete with fossil fuels. Nevertheless, the anticipated energy crisis means it is essential to develop a revolutionary PV technology with high conversion efficiency, usability and low-cost as soon as possible.
Our team's research into PV cells focuses on 5 key areas including silicon- based PV cells, silicon thin-film PV cells, organic PV cells, CIGS PVS cells and high-quality Ge substrates for III-V PV cells (high quality Ge thick-film grown on silicon substrate) in order to advance the development of PV cells.