Investigation of the vertical electrical transport in a-Si:H/nc-Si:H superlattice thin films.

Tuning the size of silicon nano-crystallites (Si-ncs) has been realized simply by controlling the thickness of the nc-Si:H sub-layer (tnc) in the a-Si:H/nc-Si:H superlattice thin films grown by low temperature plasma processing in PE-CVD. The vertical electrical transport phenomena accomplished in superlattice films have been investigated in order to identify their effective utilization in practical device configuration. The reduced size of the Si-ncs at thinner tnc and the associated band gap widening due to quantum confinement effects generates the Coulomb potential barrier at the a-Si/nc-Si interface which in turn obstructs the transport of charge carriers to the allowed energy states in Si-ncs, leading to the Poole-Frenkel tunneling as the prevailing charge transport mechanism in force. The advantages of the conduction process governed by the Poole-Frenkel mechanism are two-fold. The lower barrier height caused by the a-Si:H sub-layer in the superlattice than the silicon oxide sub-layer in conventional structures enhances the conduction current. Moreover, increasing trapped charges in the a-Si:H sub-layer can arbitrarily increase the current conduction. Accordingly, a-Si:H/nc-Si:H superlattice structures could provide superior electrical transport in stacked layer devices e.g., multi-junction all silicon solar cells.

Spectroscopic and microscopic studies of self-assembled nc-Si/a-SiC thin films grown by low pressure high density spontaneous plasma processing.

In view of suitable applications in the window layer of nc-Si p-i-n solar cells in superstrate configuration, the growth of nc-Si/a-SiC composite films was studied, considering the trade-off relation between individual characteristics of its a-SiC component to provide a wide optical-gap and electrically conducting nc-Si component to simultaneously retain enough crystalline linkages to facilitate proper crystallization to the i-nc-Si absorber-layer during its subsequent growth. Self-assembled nc-Si/a-SiC thin films were spontaneously grown by low-pressure planar inductively coupled plasma CVD, operating in electromagnetic mode, providing high atomic-H density. Spectroscopic simulations of ellipsometry and Raman data, and systematic chemical and structural analysis by XPS, TEM, SEM and AFM were performed. Corresponding to optimized inclusion of C essentially incorporated as Si-C bonds in the network, the optical-gap of the a-SiC component widened, void fraction including the incubation layer thickness reduced. While the bulk crystallinity decreased only marginally, Si-ncs diminished in size with narrower distribution and increased number density. With enhanced C-incorporation, formation of C-C bonds in abundance deteriorates the Si continuous bonding network and persuades growth of an amorphous dominated silicon-carbon heterostructure containing high-density tiny Si-ncs. Stimulated nanocrystallization identified in the Si-network, induced by a limited amount of carbon incorporation, makes the material most suitable for applications in nc-Si solar cells. The novelty of the present work is to enable spontaneous growth of self-assembled superior quality nc-Si/a-SiC thin films and simultaneous spectroscopic simulation-based optimization of properties for utilization in devices.

Beads and Beyond: An Observational Study to Generate Real World Evidence on Various Brands of Itraconazole.

Background: Rising number of the nonresponding dermatophytic infections raises deep concerns among the dermatologists across the nation. Variations in the quality of itraconazole may be a contributing factor to nonresponse in certain dermatophytic infections. This article will address this issue in a simple way of analyzing things in an OPD and may help us in being aware and taking the right foot forward. Aims and Objectives: To assess the quality of itraconazole brands by observing the morphological properties of pellets/beads in different brands. Methods: In this study, 10 brands of itraconazole that are commonly used in clinical practice were randomly selected. Pellet counts and qualitative morphological analysis of pellets as size (small, large, or mixed), shape (uniform or nonuniform), and presence of amorphous material was performed by three independent observers. Also, dissolution profile of some brands was assessed by adding the pellets in equal quantity of water. Results: The pellet counts of brands varied from 856 pellets per capsule in brand 1 to 109 pellets per capsule in brand 8. Brand 1, brand 2, and brand 7 pellets were small and uniform in morphology. Brand 3, brand 4, and brand 10 pellets were mixed in size but uniform in morphology. Brand 9 pellets were mixed and nonuniform whereas brand 5, brand 6, and brand 8 pellets were mixed in size, nonuniform in shape, and had presence of amorphous material. Dissolution test revealed that brand 5 dissolved rapidly and turned clear water color to milky white. Conclusion: A simple dermoscopy examination of itraconazole pellets may provide thoughtful insights about the quality of itraconazole brand. It may be considered as routine practice for all dermatophytic infection planned for treatment with itraconazole.

Epitheloid hemangioma: a report of two cases.

We report two cases of epitheloid hemangioma presented with multiple nodular lesions over head and neck region. One of them gave history of bleeding on minor trauma. Pyogenic granuloma was considered as a differential diagnosis from the morphological appearance and history of bleeding. Nodular leprosy, sarcoidosis, and secondary syphilis were also considered. Histopathological examination of both was typical of epitheloid hemangioma, an entity commonly overlooked clinically due to its rarity.