Visible photo- (PL) and electroluminescence (EL) were observed at room temperature from nanocrystalline Si (nc-Si) thin film; nc-Si was electrochemically formed in HF aqueous solution from boron doped microcrystalline Si (μc-Si) deposited by a rf plasma chemical vapor deposition method on a glass substrate with a SnO2 transparent conductive layer. From the scanning electron microscope images, the ‘‘pore’’ structure is not found on the surface of the nc-Si thin film. PL occurs with a broadband spectrum peaking at an energy around 1.7 eV and its spectral shape resembles that of conventional porous Si made from a crystalline Si substrate. The dependence of PL intensity on crystalline volume fraction in μc-Si implies that the quantum size effects operate in the emission process in nc-Si. Visible EL emission was observed in a p-i-n heterostructured diode consisting of the nc-Si and amorphous layers with the spectral peak energy of 1.8 eV.
Visible electroluminescence (EL) has been achieved on the entirely solid state thin film light emitting diode (TFLED) employing electrochemically anodized nanocrystalline Si (nc-Si) as a light emitting active layer. The TFLED consisting of p-type nc-Si, and intrinsic and n-type amorphous layers was fabricated on a SnO2-coated glass substrate. The nc-Si was formed in HF aqueous solution from boron doped microcrystalline Si (μc-Si) deposited by rf plasma chemical vapor deposition (CVD). The TFLED exhibits clear rectification with a forward threshold voltage of about 1.5 V, whereas visible EL emission is observed upon applying reverse bias voltages. The diode ideality factor is more than 2, and the light output increases with the square of the diode current. The EL emission color is orange-red and the spectral peak energy is 1.8 eV.
Studies of micro-cutting have so far largely been carried out on single-phase materials. Due to the size effect, the workpiece material microstructure can have a significant influence on the cutting force, chip formation and surface quality. Previous investigations have shown that hard particles in materials such as aluminum alloy can play a significant role in the generation of defects such as cracks and voids on the work surface. This paper will examine the extent of the problem during the micro-cutting of Al6061 T6 and propose how it can be mitigated.
The classical and semiclassical position entropies for the three-dimensional Coulomb problem are obtained explicitly for all values of angular momentum, without recourse to asymptotic expansions. The analytic results relate the classical period of the motion, total energy, position entropy and dependence upon the principal quantum number n. It is demonstrated that the position entropy varies with energy E as ln|E| −1 .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.