A. Dutt

Development of Optimal Nanocrystalline Absorption Layer for Thin Film Silicon Solar Cell Applications

To obtain an optimum absorption layer based on hydrogenated polymorphous and nanocrystalline silicon thin films in a plasma-enhanced chemical vapor deposition, radio frequency (RF) power was varied from 25W to 100W using a mixture of dichlorosilane and hydrogen. By Raman spectroscopy, the crystalline fraction was found to be varied from 7% to 69%, and RF power value of 75W was found to be suitable with an appropriate mixture of amorphous and crystalline phases, respectively. Thickness measurements performed by profilometry were cross-checked with the value obtained from the cross-sectional scanning electron microscopy micrographs. Micrographs obtained using high-resolution transmission electron microscopy confirmed the presence of silicon nanocrystals in the range of 2–5nm with a strong probability of confinement effect. B and gap value of 1.55eV at 75W upheld the suitability of this particular RF power for active absorption layer, which has also shown maximum photosensitivity.

Size distribution and visible luminescence of silicon nanoparticles embedded in SiNx thin film: Role of RF power in PECVD

This paper presents, the studies of the influence of (radio frequency) RF power on the size distribution and visible photoluminescence (PL) of SiNx thin film deposited at 300∘C of substrate temperature by plasma enhanced chemical vapor deposition. RF power was varied (5–50W), and its aftereffect on the optical properties of thin films was investigated. By increasing the RF power between 5W and 25W, main PL peak showed a red shift with an increase in PL intensity, which is associated with an increase in the silicon nanocrystals size and density, respectively. Results obtained were confirmed with High-resolution transmission electron microscopy micrographs and from the statistical calculations. By attaining a precise RF power value, stable silicon nitride thin film with suitable optical properties can be achieved for the potential fabrication of optoelectronic devices.

Anticipated graded emitter design for the efficient type HIT solar cells

In this work, we present the optoelectronic properties in polymorphpus silicon thin films grown by plasma Enhanced Chemical Vapor Deposition (PECVD), starting from diclosorsilane and hydrogen as precursor gases. Variation in the band gap from 1.66 to 2.0 eV as a function of different deposition conditions were obtained. Raman spectrocopy was used to determine the crystalline fraction in the polymorphous silicon thin films. On the other hand the relation of photosensitivity with the RF power and the behavior of diffusion length were studied. A model of a new type of HIT solar cells with band gap and doping gradient is proposed.

The role of crystalline fraction on the photoconductive response in polymorphous silicon materials for thin films solar cells

In the present work, we show that controlling structural and chemical parameters is possible to modify the optoelectrical properties of hydrogenated Polymorphous Silicon thin films (pm-Si:H), grown by Plasma Enhanced Chemical Vapor Deposition (PECVD). From the Raman analysis, we observe that the nanocrystalline phase is present in all deposited films. On the other hand, with XPS it is seen that an oxidation process takes place for the samples grown at high hydrogen dilutions, while the others samples only show superficial oxidation after ambient exposure. The samples were exposured to light soaking treatment for long time and resultantly, shown different behavior in photoconductivity response.