The electrical conductivity of hydrogenated nanocrystalline silicon investigated at the nanoscale

Abstract

Hydrogenated nanocrystalline silicon (nc-Si:H) is a multiphase, heterogeneous material, composed of Si nanocrystals embedded in an amorphous matrix. It has been intensively studied in the last few years due to its great promise for photovoltaic and optoelectronics applications. The present paper aims to study the current transport mechanisms in nc-Si:H by mapping the local conductivity at the nanoscale. The role of B doping in nc-Si:H is also investigated. Conductivity maps are obtained by atomic force microscopy using a conductive tip. Differences and similarities between intrinsic and doped nc-Si:H conductivity maps were observed and these are also explained on the basis of recently published computational studies.

Electrical properties of silicon carbide/silicon rich carbide multilayers for photovoltaic applications

“…These features can be related to clusters formed by Si or SiC nano-crystals, as in [5] cluster formation is observed. This map presents a pronounced difference with respect to the case of nc-Si:H [26][27][28], where in the intrinsic layers all the Si NCs clusters showed similar conductivities, but different from the matrix one. In the present case the different conductivity of clusters can be related to compositional variation (Si or SiC content), and/or to unintentional doping by contamination with N and O.…”

Conductive atomic force microscopy on carbon nanowalls

“…Our experience shows that the best quality images were measured at a soft set-point when minimum tip damage occurs. The minimal set-point prevents artifacts related to the conductive layer abrasion [12]. As in the case of common tapping mode, the TR-TUNA allows one to measure the phase shift between excitation and response of the cantilever.…”

Role of the tip induced local anodic oxidation in the conductive atomic force microscopy of mixed phase silicon thin films

“…Sample A was measured by Veeco Dimension 3100 AFM. All AFM results were performed in contact mode using the Cr/Pt coated Si cantilevers (BudgetSensors ContE) with force constant 0.2 N/m and with fresh cantilever to avoid the conductive layer abrasion [1,10]. Local current flowing through the grounded cantilever was induced by a dc V bias applied to the bottom of the silicon substrate.…”

“…The first measurements of μc-Si:H by the Conductive AFM (C-AFM) were done in ultra high vacuum (UHV) on in-situ grown samples to avoid the native surface oxide [1,3]. An easier approach of the C-AFM in ambient air conditions was used for silicon films [4][5][6][7][8][9][10] as well as for other materials [11][12][13][14][15]. In air the silicon surface is always covered by a thin native oxide [16], lowering the observed local currents [4].…”