I am studying the electrical instability when applying positive bias stress to the a-IGZO TFT.
At this point, the transfer curve moves in the negative direction, and I think it's the influence of oxygen vacancy.
From my understanding of oxygen vacancies, I understand that there are two types of shallow/deep states.
If PBS is applied, can electrons be released from oxygen vacancies in the deep state?
I don't know why the transfer curve moves negative direction when PBS applied.
ALso, In paper [A Unified Degradation Model of Elected-Metal Oxide (EMMO) TFTs Under Positive Gate Bias With or Without an Illumination] that i read, said that electrons and Vo2+ concentrations in the channel should be balanced. i wonder why this phenomenon occurs.
Oxygen vacancies can play a role in the electrical instability of a-IGZO TFTs under positive bias stress. When oxygen vacancies are present in the channel, they can act as trap sites for electrons. These trapped electrons can form either shallow or deep states, depending on their energy level relative to the conduction band minimum of the semiconductor material.
Under positive bias stress, electrons can be released from the oxygen vacancies in the deep states and become mobile in the channel. This can lead to an increase in the conductivity of the material and a shift in the threshold voltage of the TFT towards more negative values, which may explain the negative shift in the transfer curve that you observed.
The balance between electrons and Vo2+ concentrations in the channel is important because excess oxygen vacancies can lead to a reduction in the number of available charge carriers and a decrease in the conductivity of the material. On the other hand, an excess of electrons in the channel can lead to an increase in the concentration of Vo2+ ions, which can act as trap sites and further exacerbate the electrical instability of the TFT.
Overall, the presence of oxygen vacancies can play a complex role in the electrical properties of a-IGZO TFTs, and their influence on the device behavior may depend on a variety of factors such as the concentration and energy level of the trap states, the bias conditions, and the balance between electrons and Vo2+ ions in the channel.
N. Rajamanickam I have one more question. In most papers say that applying Vg/Vd stress to IGZO TFT causes the temperature inside the channel to rise due to the influence of the drain current. Also, I heard that oxygen vacancies increase due to this effect, is this correct?
Also, it is said that the generated neutral oxygen vacuum is given electrons to a conduction band to become positively charged oxygen vacuum, so I wonder why you can give electron.
- Badges
- Science topic
- Similar topics
- Linguistics
- Composition Studies
- Publication