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Hydrogenated amorphous substoichiometric silicon carbon alloys (a-SiC:H) with and without embedded Ge nanoparticles (NPs) have been prepared by plasma enhanced chemical vapour deposition combined with in-situ Ge evaporation and annealing on semi-transparent boron doped nano-crystalline diamond coated Ti grids. The presence of Ge NPs embedded in the amorphous phase has been confirmed by transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses. Current-voltage (I–V) characteristics and near infrared electroluminescence (EL) spectra were measured to compare performance of diodes. The relatively strong EL appears in diodes with integrated Ge NPs near the direct band-gap transition of Ge at about 0.82 eV with an intensity strongly correlating with current density. However, it has also been found that Ge NPs integrated into a-SiC:H significantly deteriorates diode I–V characteristic.

We present the optical absorption spectra of metal nanoparticles prepared by thermal annealing of the ultra thin metal films evaporated on polycrystalline ZnO films. The surface morphology, particle size and density were monitored by the atomic force microscopy (AFM) and scanning electron microscopy (SEM). ZnO films with the surface roughness about 10 nm rms deposited on sapphire and immersed in the transparent liquid show negligible optical reflectance, interferences and light scattering and are transparent at wavelengths above 400 nm. The optical absorption of ZnO film in UV region allows to calibrate the photothermal deflection spectra (PDS) both with and without metal nanoparticles and to estimate with high precision the optical absorptance of metal nanoparticles in the visible and near infrared region. The optical absorptance spectra of gold nanoparticles embedded in the non-absorbing medium can be simulated by effective medium approximation-EMA (Maxwell-Garnett model). The maximum of the localized plasmon resonance shifts to longer wavelengths (red shift) when the metal nanoparticles are more tightly packed in the matrix, whereas the size of the nanoparticles determinate the width of the resonance peak. The electron scattering cross section of Au nanoparticles observed by SEM is about two times larger than their diameter.1 Introduction Thin film silicon solar cells require light trapping for high performance because of weak absorption at long wavelengths. The light trapping has been usually achieved by depositing rough polycrystalline conductive oxide (TCO) film on glass substrate followed by the active layers, second TCO film and finally metal backreflector. The back contact composed from the rough TCO film covered by the metal film scatters and reflects light, which was not absorbed back into the solar cell [1]. The optical properties and efficiency of thin film silicon solar cells with rough interfaces were modelled in our previous paper [2].While the submicron surface roughness increases light scattering, the rough metal/semiconductor interface absorbs significantly in a broad optical spectral range deteriorating the textured metal mirror performance [3]. Generally, the optical properties of textured metal films and metal nanoparticles are dominated by collective oscillation of conducting electrons in bulk and at the surface. On flat metal surface/air interface the optical absorption in near infrared region is low, but it

Методом плазмохимического осаждения сформированы четыре пары p-i-n-структур на основе pm-Si:H (полиморфного Si : H). Структуры в каждой паре выращивались на одной подложке так, что одна из них была без Ge в i-слое, а другая содержала Ge, который осаждался слоем толщиной 10 нм методом вакуумного напыления. Пары различались между собой температурой подложки при осаждении Ge, которая была 300, 350, 400 и 450 oC. Данные электронной микроскопии показали, что структуры, полученные при 300 oC, содержали нанокристаллы Ge (nc-Ge), центрами зарождения которых являлись нанокристаллические включения на поверхности pm-Si:H. Концентрация nc-Ge увеличивалась c возрастанием температуры. Исследование вольт-амперных характеристик показало, что наличие Ge в i-слое уменьшало плотность тока короткого замыкания в p-i-n-структурах, когда они использовались как солнечные элементы, тогда как наблюдалось увеличение тока под действием освещения при обратном смещении. Полученные результаты согласуются с известными данными для структур с кластерами Ge в Si, согласно которым кластеры Ge увеличивают коэффициент поглощения света, но также увеличивают и скорость рекомбинации носителей. DOI: 10.21883/FTP.2017.10.45024.8547