Boron doping and post-hydrogenation effects on optical gaps and urbach tails of amorphous hydrogenated silicon films prepared by chemical vapour deposition

Nanostructured CdSe Films in Low Size-Quantization Regime: Temperature Dependence of the Band Gap Energy and Sub-Band Gap Absorption Tails

“…The higher the size quantization effects (which are often accompanied by higher ε and δ values), the higher the value of X in , as revealed by a direct comparison of the nanostructured systems addressed in our present and previous studies. It is worth noting, however, that such high values for the Urbach energies (i.e., Urbach tails with large widths) have been already found for particular materials, mostly with amorphous or partially crystalline character. − Nanostructured thin films, therefore, behave similarly as amorphous materials in this respect.…”

“…As already implied, however, though the sub-band gap absorption has been studied a lot in the case of macrocrystalline and amorphous materials, − emphasizing many aspects as well as the influence of a number of external parameters on the UM absorption tails, the number of studies has been much smaller in the case of nanostructured semiconductors (3D QD assemblies, in particular) and also in the case of thin films. As we have already argued before, however, it is of certain importance for both fundamental aspects of physical chemistry, materials science, and the potential applications of semiconductor quantum dot thin films to follow the evolution of the sub-band gap absorption tails with both temperature and controlled particle size reduction.…”

Temperature Dependence of the Band-Gap Energy and Sub-Band-Gap Absorption Tails in Strongly Quantized ZnSe Nanocrystals Deposited as Thin Films

“…Note, however, that, besides on the degree of structural disorder, the exact values of the Urbach energies for particular materials also depend on other material-dependent parameters (eq ), such as σ 0 and the phonon energy E p . Also, even for one and the same material, the Urbach energy varies even in the case of crystals characterized with the same average size but obtained by different chemical methods. − It is worth noting, however, that such high values for the Urbach energies (i.e., Urbach tails with large widths) have been already found for particular materials, mostly with an amorphous or partially crystalline character. − It could be, therefore, concluded that nanocrystalline thin films behave similarly as amorphous materials in this respect. To the best of our knowledge, however, this is the first experimental study in which the validity of the Urbach−Martienssen rule in the case of nanocrystalline thin films has been demonstrated.…”

“…[35][36][37][38][39][40][41][42] It is worth noting, however, that such high values for the Urbach energies (i.e., Urbach tails with large widths) have been already found for particular materials, mostly with an amorphous or partially crystalline character. [44][45][46][47][48][49][50][51][52][53] It could be, therefore, concluded that nanocrystalline thin films behave similarly as amorphous materials in this respect. To the best of our knowledge, however, this is the first experimental study in which the validity of the Urbach-Martienssen rule in the case of nanocrystalline thin films has been demonstrated.…”

“…The doping, hydrogenation, and postdeposition annealing influences on the optical absorption edge of various amorphous materials have been studied as well. [44][45][46][47][48][49][50][51][52][53] It is, however, of certain importance for both the fundamental physical chemistry and materials science and the potential applications of the semiconductor QD thin films to follow the evolution of these absorption tails upon controlled particle size reduction as well. It is exactly this aspect of semiconducting nanocrystalline materials that the present paper is devoted to.…”