How is the band gap of a material determined?

Optical ellipsometry spectroscopy, UV-Vis spectroscopy as well as the electrical measurement method, can be used to calculate the bandgap energy. One can find the slope of the ( lnR vs 1/T) graph, then calculate the Eg-value where: ( Eg = 2 k. slope), and k is the Boltzmann constant.

Why is TiO2 a semiconductor?

The oxygen vacancies act as electron donors, thus TiO2-x is an n-type semiconductor, in contrast with p-type semiconductors which contain electron acceptors and where the charge carriers are holes rather than electrons [23].

What is the difference between anatase and rutile TiO2?

The key difference among them is in their appearance. Anatase Titanium Dioxide is colorless, whereas Rutile Titanium Dioxide is usually found in dark red appearance. Rutile titanium dioxide is optically positive, whereas Anatase titanium dioxide is optically negative.

Does TiO2 have a direct band gap?

TiO2 Anatase is an indirect band gap semiconductor and possesses a band gap value of ~3.2-3.35 eV if it is in the thin film state.

Is TiO2 p-type?

Hi Ashish Kumar , TiO2 can be both a p-type or n-type conductor. This is highly dependant on the dopant/impurity concentration.

Is germanium a semiconductor?

Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbors silicon and tin. Pure germanium is a semiconductor with an appearance similar to elemental silicon.

What is the TiO2 band gap type?

TiO2 Anatase is an indirect band gap semiconductor and possesses a band gap value of ~3.2-3.35 eV if it is in the thin film state. The following refs. might be of help to you: i) Z. Wang, U. Helmersson, P.O. Ka¨ll, Thin Solid Films 405 (2002) 50. If you study of TiO2 nanoparticles this paper will be useful for you.

Which is the most common semiconductor with a band gap?

TiO 2 is a wide band gap semiconductor, with three common polymorphs; rutile, anatase and brookite. The ground state, rutile, is easy to make and the most common found in industry, while brookite is the least. As a result, rutile has been studied extensively, and its band gap energy is the most well-known band gap of 3.0 eV.

Why is the catalytic efficiency of TiO 2 low?

On the other hand, the catalytic efficiency of TiO 2 in the wider spectrum of solar energy is still low because of its wide band gap and high recombination rate of photoinduced electrons and holes.

How can band gap states improve photocatalytic performance?

However, few approaches are able to introduce band gap states and improve photocatalytic performance simultaneously. Introducing band gap states by creating surface disorder can incapacitate reactivity where unambiguous adsorption sites are a prerequisite.