Band gap energy and Urbach tail studies of amorphous, partially crystalline and polycrystalline tin dioxide

Optical properties of boron carbide (B5C) thin films fabricated by plasma-enhanced chemical-vapor deposition

“…The McLean method can be used to approximate the interband transition probabilities for various types of optical transitions in semiconductors: [21][22][23] …”

The Influence of the Substrate Temperature on the Properties of Solar Cell Related Thin Films

“…Other reasons include the change in the density of charge carriers with the substrate temperature and the movement of dopants from grain boundaries to the grains to be effectively incorporated in the crystal lattice. A slight increase in the optical bandgap energy with substrate temperature was observed by different authors [8,12,18,42]. For spray-deposited CdS:In thin films we [8] found that E g slightly increases with the substrate temperature.…”

“…We found that the E g = 2.42 eV for a film deposited at 355 °C and E g = 2.44 eV for a film deposited at 490 °C. Bilgin et al [18] [42] observed this increase of E g with substrate temperature for tin dioxide thin films prepared by the spray pyrolysis technique. Values of E g = 2.51-3.05 eV where obtained for amorphous and partially polycrystalline thin films prepared at T s = 340-410 °C, and E g = 3.35-3.43 eV for polycrystalline tin dioxide thin films produced at T s = 420-500 °C.…”

“…But it is important to notice that the thickness of their films is not constant, which means that the decrease in bandgap is also related to the increase in film thickness not only to the increase in substrate temperature. Urbuch tail width E e which is known to be constant or weakly dependent on temperature and is often interpreted as the width of the tail of localized states in the band gap [43] was also found to be randomly affected by the substrate temperature as shown by Bilgin et al [18] for CdS thin films prepared by USP technique, where it has values in the range 122-188 meV for substrate temperatures in the range 473-623 K. But Melsheimer and Ziegler [42] observed a decrease of E e with substrate temperature for spray-deposited tin dioxide thin films. For amorphous and partially polycrystalline films prepared at T s = 340-410 °C, it decreased from 530 to 350 meV.…”

Techniques for the Study of the Electronic Properties.

“…77,78 The acquisition of spectra can be very fast, and chemical transformations can be followed as a function of time. 88,89,90 Valence Photoemission.…”