Organic/inorganic heterostructures are an emerging and interesting field of research for optoelectronics. In this work, an efficient organic/inorganic hybrid heterojunction between PEDOT:PSS and n-type Silicon has been fabricated for optoelectronic applications. Samples with varying thickness of PEDOT:PSS were prepared by spin coating technique and the electrical conductivity of organic layers was modified using DMSO as additive. Post fabrication, the hybrid heterostructures were treated with HNO 3 vapor so as to enhance the conductivity of the organic layer. Surface treatment with HNO 3 was found to lower the roughness of the organic layer and enhance the transparency of the layer. I-V characteristics reveal optimized behavior of HNO 3 treated PEDOT:PSS layer with a low Ideality factor (n~3.2) and a barrier height (Φ B ) of 0.8 eV. The findings of the study provide a promising efficient method to enhance the electrical and device properties of PEDOT:PSS/n-Si heterostructures for optoelectronic applications.

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InGaN/GaN heterostructures were grown on c-plane sapphire substrates using metal organic chemical vapour deposition by varying the trimethylindium flow rate as 7, 10 and 14 µmole/min. The structural, morphological, optical and electrical properties of InGaN layers were investigated. Crystalline quality, dislocation densities comprising of screw and edge types in InGaN and GaN layer have been analyzed using High-Resolution X-ray Diffractometer (HRXRD). The composition of Indium (In) in the InGaN layers was estimated around 8-10% which was found to be dependent on the In flow rate. The strain between InGaN and underlying GaN layer have been analyzed through reciprocal space mapping studies along the (1 0 -1 5) plane in InGaN/GaN heterostructures. The features of V and trench defects were observed using scanning electron microscopy and atomic force microscopy respectively. The V and trench defect density has been correlated with the pre-existing threading dislocation density estimated using HRXRD measurements. Also the trench defects were observed to be a coalescence of V defects in InGaN layers. The photoluminescence results showed that band edge emission peaks of three different points (primary flat, centre, and Edge) were observed. These peak variations were found to be red shift behavior in all three points. These variations were due to the fluctuations in the Indium composition and corresponding trench & V defects respectively. The Hall measurements exhibit an alteration in semiconducting behavior with respect to V and trench defect surrounded InGaN layers. And also realized that compressive strain in underlying GaN can lead the high sheet concentration compared to the tensile strained underlying GaN layer. It clearly suggests that the V and trench defect surrounded InGaN layers contain the suitable candidates for next generation optoelectronics applications.

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