Eun Hyun Kim

15.2: 2.0 inch a‐Si:H TFT‐LCD with Low Noise Integrated Gate Driver

We developed a 2.0 inch, QCIF (160×128×RGB), a-Si:H TFT-LCD with a low noise gate driver integrated on glass substrate. By simulation and measurement, the proposed gate driver was found to be noise-free compared to conventional one. A new gate driver can make it possible to perform operation regardless of the voltage coupling from other voltage sources.

Formation and analysis of disk-shaped grains by Ni-mediated crystallization of amorphous silicon

Disk- and needle-shaped grains can be seen in polycrystalline silicon (poly-Si) made by Ni-mediated crystallization of amorphous silicon (a-Si). A major parameter to give the difference of grain structure is the Ni area density on a-Si. However, there are many other parameters such as heating rate and structure of a-Si to affect the grain structure. The use of Ni density of ∼1013cm−2 on a-Si for the crystallization gives the disk-shaped grains. There is no amorphous phase in the disk-shaped grains which are composed of well-aligned needles. On the other hand, the poly-Si has some amorphous phase inside when it was crystallized into needlelike rods. It is found that the width of needles in the disk-shaped grains is smaller than that of needlelike crystallites. The Ni atoms are at the grain boundaries formed by the collisions of neighboring grains.

Location control of giant silicon grains using organic lenses

We studied the location control of a giant grain of polycrystalline silicon produced by Ni-mediated crystallization of amorphous silicon (a-Si) using a cap layer. An organic lens made of acryl was used for the focusing of light for the seed formation and subsequent crystallization. A single grain 62μm in diameter was made using an 80-μm-square SiNx cap layer on the a-Si. The position of a thin-film transistor (TFT) on a grain can be controlled, so that a single grain TFT can be fabricated at a predetermined position without use of the laser annealing technique.

Growth of (100)-Oriented Polycrystalline Si Film by Ni-Mediated Crystallization of Thin Amorphous Silicon

We studied the Ni-mediated crystallization of amorphous silicon (a-Si) as a function of its thickness. It was found that the orientation of the poly-Si changed from [110] to [001] when its thickness reduced down to 16 nm.This was confirmed by the analysis of electron backscattered diffraction pattern. The growth of (100)-oriented poly-Si is due to the predominant formation of [001] NiSi 2 nuclei in a thin a-Si network because of its smaller crystalline size compared to that of [110] nuclei.

A Method of Forming a Polycrystalline Si with the Biomolecule Ferritin

We studied the metal-induced crystallization of a-Si using a Ni-ferritin molecule of 7 nm diameter. The Ni-ferritin molecules were coated onto the SiN x /amorphous silicon (a-Si)/buffer/glass and it was heated at 580°C for 20 h for crystallization after UV burning of the biomaterial. It was found that the grain size of poly-Si increases with decreasing the ferritin density. A grain size of ∼220 μm was achieved, and its surface roughness was 2.1 nm.

Enlargement of grain in poly-Si by adding Au in Ni-mediated crystallization of amorphous Si using a SiNx cap layer

We have studied the effect of Au addition on Ni-mediated crystallization of amorphous silicon(a-Si) using a silicon–nitride (SiNx) cap layer. The Ni and Au particles were sputtered on the SiNx∕a-Si and then the samples were heated for crystallization at a temperature of 550 °C. We achieved disk-shaped grains and found that the grain size increased with increasing Au density when the Ni density was fixed at 2.45×1014∕cm2. We achieved a grain size of ∼45μm, however the a-Si could not be crystallized when Au density is higher than Ni density.