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Fixed drug eruption (FDE) is one of the common types of cutaneous adverse drug reaction. This study was conducted to study the common types of drugs causing FDE and to find the management pattern of FDE in a tertiary care teaching hospital. In this study we found that orindazole (24%) and co-trimoxazole (20%) had higher incidence of FDE. Sixty eight percent of patients developed post inflammatory pigmentation. The most common clinical presentations was black patch in 44%, followed by bulla with erythematous patch in 20% of pigmented patches. Topical steroids, antihistaminic and oral corticosteroids were the common drugs used in the management of fixed drugs eruptions. The most common affected site was lip in 33.3% followed by trunk in 21%. The most common age group was 11-20 year followed by 21-30 year, fifty-one cases were seen in male. Keywords: Fixed drug eruption, Cutaneous Adverse drug reaction, Pigmentation.

A wide optical gap nanocrystalline silicon (nc-Si) dielectric material is a basic requirement at the n -type window layer of nc-Si solar cells in thin film n-i-p structure on glass substrates. Taking advantage of the high atomic-H density inherent to the planar inductively coupled low-pressure (SiH 4 + CH 4 )-plasma, development of an analogous material in P-doped nc-Si–QD/a-SiC:H network has been tried. Incorporation of C in the Si-network extracted from the CH 4 widens the optical band gap; however, at enhanced PH 3 -dilution of the plasma spontaneous miniaturization of the nc-Si–QDs below the dimension of Bohr radius (∼4.5 nm) further enhances the band gap by virtue of the quantum size effect. At increased flow rate of PH 3 , dopant induced continuous amorphization of the intrinsic crystalline network is counterbalanced by the further crystallization promoted by the supplementary atomic-H extracted from PH 3 (1% in H 2 ) in the plasma, eventually holding a moderately high degree of crystallinity. The n -type wide band gap (∼1.93 eV) window layer with nc-Si–QDs in adequate volume fraction (∼52%) could furthermore be instrumental as an effective seed layer for advancing sequential crystallization in the i -layer of nc-Si solar cells with n-i-p structure in superstrate configuration.

The growth of nc-Si:H from the SiH4 plasma inherently proceeds through a defective and amorphous incubation layer, originating due to the lattice mismatch between the substrate and Si material. In the current investigation, a-Si:H/nc-Si:H thin film super-lattice structures have been fabricated at very low temperature (∼180 °C), using single step conventional plasma processing. In this intriguing technique the a-Si:H barrier sub-layer itself operates as an effective incubation layer which facilitates growing the nc-Si:H active sub-layer possessing adequate crystallinity inside a very low thickness (tnc) of even ≥3 nm, and the sudden discontinuity in growth of the active layer confines the size of Si-ncs within the dimension of this active sub-layer thickness. The superlattice structure of the ultimate network has been evidenced from small angle XRD (SAX) measurements, whereas the nature of crystallinity has been studied by ellipsometry, Raman spectroscopy and electron microscopy. This simple yet compelling technique seems to have enormous technological implications taking the advantage of the quantum confinement effect in low dimensional silicon nano-crystallites within very thin superlattice structures.

Spontaneous miniaturization of self-assembled nc-Si-QDs with preferred 〈220〉 crystallographic orientation and a rapid synthesis of superior quality nc-Si-QD/a-SiC thin films with enhanced crystallinity, maintaining a combination of wide optical gap and simultaneous high electrical conductivity, has been attained from (SiH4 + CH4)-plasma, without any additional H2-dilution in inductively coupled plasma CVD. The optical gap widens due to the Si–C bonds in the amorphous network and the increased quantum confinement effect on the miniaturized Si-QDs. CH4 acts as the dual source of both C and atomic-H. High density of atomic-H available in the planar ICP promotes simultaneously the Si crystallization and its growth along the thermodynamically favored 〈220〉 crystallographic orientation, thereby contributing easier electrical transport, particularly at devices in superstrate configuration. After imminent doping, these could be efficiently utilized as window layers in third generation all-silicon solar cells.

In order to facilitate widening in optical band gaps utilizing quantum size-effects in silicon nano-crystals (Si-ncs) of a few nanometers in dimension, self-assembled Si-ncs embedded in an a-Si matrix were grown within a-Si:H/nc-Si:H superlattice (SL) thin films produced by alternating sub-layers of a-Si:H and nc-Si:H from (SiH4 + H2)-plasma in PE-CVD at 180 °C, without post-deposition annealing. The growth of Si-ncs extending all through the nc-Si:H sub-layer thickness is terminated by the alternate deposition of an a-Si:H barrier layer during each cycle and the average size of the Si-ncs with a narrow size distribution is tuned by controlling each nc-Si:H sub-layer thickness. Significantly high-density tiny Si-ncs are grown even within an ultra-thin (∼3 nm) nc-Si:H sub-layer and that has been made possible via an ingenious approach, by utilizing the underneath of an a-Si:H sub-layer as the virtual incubation layer at a very specifically chosen parametric condition, during each cycle of periodic deposition. On systematic thinning of the nc-S:H active layer within 8–3 nm, a remarkable increase in optical absorption at near-UV photon energies along with simultaneous optical band gap widening within 1.89–2.04 eV demonstrate that the quantum size-effect in Si-ncs plays a key role. Subsequent lowering in the defect states identifies the nc-Si:H/a-Si:H SL-films as a superior material for use in devices, including as i-layers in triple-junction all-silicon solar cells.

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.

Nano-crystalline silicon quantum dots (Si-QDs) embedded in the phosphorous doped amorphous silicon carbide (a-SiC) matrix has been successfully prepared at a low temperature (300 °C) by inductively coupled plasma assisted chemical vapor deposition (ICP-CVD) system from (SiH4 + CH4)-plasma with PH3 as the doping gas. The effect of PH3 flow rate on structural, optical and electrical properties of the films has been studied. Phosphorous doped nc-Si–QD/a-SiC films with high optical band gap (>1.9 eV) and superior conductivity (~10−2 S cm−1) are obtained, which could be appropriately used as n-type window layers for nc-Si solar cells in n-i-p configuration.

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.

Thin films of c-Si QDs embedded in a-SiOx dielectric matrix was achieved at a low temperature ∼400°C, from one step process by reactive rf magnetron co-sputtering of c-Si wafer and pure SiO2 targets, in the (H2+Ar)- plasma. Formation of a double-barrier structure has been primarily identified from the SAX data and exclusively confirmed from the resonant tunneling current appearing in the J-E characteristic curve peaks, determined by the discrete energy levels of c-Si QDs, at which it could be used as energy selective contacts in hot carrier solar cells.

Thin films of c-Si–QDs embedded in an a-SiOx dielectric matrix forming arrays of double barrier structures have been fabricated by reactive rf-magnetron sputtering at ∼400 °C, without post-deposition annealing. The formation of larger size c-Si–QDs of reduced number density in homogeneous distribution within a less oxygenated a-SiOx matrix at higher plasma pressure introduces systematic widening of the average periodic distance between the adjacent ‘c-Si–QDs in a-SiOx’, as obtained by X-ray reflectivity and transmission electron microscopy studies. A wave-like pattern in the J-E characteristics identifies the formation of periodic double-barrier structures along the path of the movement of charge carriers across the QDs and that those are originated by the a-SiOx dielectric matrix around the c-Si–QDs. A finite distribution of the size of c-Si–QDs introduces a broadening of the current density peak and simultaneously originates the negative differential resistance-like characteristics, which have suitable ...

Thin films of amorphous silicon oxide (a−SiOx, x≤2) with embedded Si nano-crystals (Si-NCs) of size ∼9 nm has been successfully prepared at a low temperature ∼400°C by reactive RF magnetron sputtering of pure silica target by optimizing the H2 to Ar flow ratio. H2 dilution in the plasma induces elimination of oxygen from the precursors, promotes crystallization of Si within a−SiOx matrix and controls the size of the nanocrystals. This low temperature onestep process could facilitate fabrication of low-cost devises based on Si-NCs.

Nano-crystalline silicon (nc-Si) embedded in the amorphous silicon carbide (a-SiC:H) matrix has been successfully prepared by Inductively Coupled Plasma aided Chemical Vapor Deposition (ICP-CVD) system with silane (SiH4) as precursor gas and methane (CH4) as the carbon source with hydrogen as diluents, at a low temperature. The effect of CH4 flow rate on material properties has been investigated. Nano-crystalline silicon carbide films with high optical band gap ∼ 2.1 eV and room temperature conductivity ∼ 4.5 × 10−8 S cm−1 were obtained, which on subsequent doping could help obtaining appropriate window layers for nc-Si solar cells.

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.

Progressive development towards all-silicon solar cells insists on the top cell of the tandem structure having a wide band gap p-layer in the superstrate configuration. With the advent of nc-Si solar cells having improved stability, the efficient growth of an i-nc-Si layer of the top cell prefers a nc-p-layer as its substrate. Accordingly, a conducting crystalline silicon alloy material with a wide band gap is a basic requirement at the p-layer. The present investigation deals with the development of a nc-Si/a-SiC:H hetero-structure wherein Si–C bonds in an amorphous matrix widen the optical band gap and the embedded high density tiny Si ultranano-crystallites of mostly 〈220〉 crystallographic orientation provide high electrical conductivity as well as an enhanced optical band gap due to a quantum size effect. A typical nc-Si/a-SiC:H network is obtained that contains 47% crystallinity with a prevailing ultranano-crystalline component, [(XC)unc/(XC)nc] > 1, average crystallite size ∼3.6 nm, number density ∼1.2 × 1013 cm−2 and Si–C bond density ∼1.2 × 1022 cm−3. The hetero-structure contributes a wide optical band gap, Eg ∼ 2.07 eV, high conductivity, σD ∼ 3 × 10−10 S cm−1, σPh ∼6 × 10−8 S cm−1, Ea ∼ 0.73 eV and a very low microstructure factor R ∼ 0.075. Imminent steps for doping will indeed lead to prospective window layers in nc-Si solar cells.