This is a consequence of the higher activation energy found in our TFTs. However, this process seems not to occur to any great extent, when the negative bias stress is applied in the dark and needs the presence of light generated holes to become conspicuous. Chiang and John F. Hysteresis is considerably reduced by annealing. It is also interesting that C temperature 2 hour annealing gives complete reversible characteristics which indicates the new formed defects are not permanent.

Their friendly company influenced me to survive in this environment comfortably. In case of local uniformity, the transfer was measured from six different TFTs within one die. So, uniformity behavior of our TFTs has been presented here. Hyoung Sik Nam Dr. To overcome this difficulty, we try to study the time dependent post- fabrication annealing experiment at low temperature C.

A number of other point defects ought to be considered, following first principle calculations in ZnO [31] and a-IGZO [32].

That result shows that their TFT performance was not good. This attribute along with the amorphous nature of the material also makes IGZO TFTs compatible with flexible substrates opening up various applications. By Jin Young Jang. On the other hand, Stephan Lany and Alex Zunger [8] said that Oxygen O2 is the main donor in metal oxide semiconductor, which could be practically understood by Fig.

Negative stress shifts the transfer left with increasing the swing and mobility which may be due to the addition of new defects near the insulator interface.

igzo tft thesis

That point influenced the tvt industry to invest a lot for metal-oxide research. To know the origin of light and negative bias stress, we did some physical experiment, discussed in the next sections.


On the basis of experimental concept, it has been found that the n-type conductivity is from the native point defects [6], introduced first in ZnO. Therefore, we are left with the third mechanism: The output intensity of the phosphor was successfully modulated by the TFT. After studying several decades with silicon semiconductor, peoples were trying to invent something new which could give the better performance, easy deposition at lower temperature and lower cost than silicon.

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It suggests instead that the effect is a bulk effect in the a-IGZO film [47]. Neutralized oxygen vacancies are thinking as point defects in metal- oxide materials and that vacancy is the dominator of light and negative bias instability mechanisms.

Last of all I would like to thanks to my parents, my younger brother and also all of my friends who are living both in Bangladesh and South Korea, for giving me mental support. I would like to thanks to the authority of National Institute of International Education Korean government scholarship program organizer of Korean government and Ministry of Justice of South Korea for selecting me as a Masters scholar in this scholarship program. Help Center Find new research papers in: To find out this, I want to study the following points, o Ttft to reduce the oxygen vacancy tgesis inside the metal oxide, maintaining the higher mobility?

Van de Walle, Phys. Click here to sign up. Skip to main content. TFT semiconductor materials a-Si: For the same reason, once generated, a large fraction of these vacancies is stable at room temperature.


igzo tft thesis

Transfer characteristics measured in dark after nm UV light illumination with various duration of time. The generated electrons increase the conductivity.

But the most limited issue was the big size of transistor. May in future it will be a few of atom devices. We see interesting trends that the time dependent, positive stress effects shift the transfer characteristic right whereas negative gate stress shifts the transfer lefts.

Hyoung Sik Nam, to review my work cafefully and to gave their valuable times during my defense.

Simulation and Fabrication of a-IGZO Flexible vertical TFTs

So, we tried to introduce some experimental data in chapter III, which could provide more information on the mechanism involved. Variation of parameters according to various stresses time for V and V gate stress under UV light: This is a consequence of the higher activation energy found in our TFTs. The transconductance, IDS g1. The right shifts are consistent with negative charge trapping.

Before discussing the possible origin of these defects, we wish to compare the extracted parameters with first principles estimates.

Then Hoshino et al. The stress shifts the transfer rigidly right side.