Current-voltage characteristics in macroporous silicon/SiOx/SnO2:F heterojunctions

Abstract

We study the electrical characteristics of macroporous silicon/transparent conductor oxide junctions obtained by the deposition of fluorine doped-SnO2 onto macroporous silicon thin films using the spray pyrolysis technique. Macroporous silicon was prepared by the electrochemical anodization of a silicon wafer to produce pore sizes ranging between 0.9 to 1.2 μm in diameter. Scanning electronic microscopy was performed to confirm the pore filling and surface coverage. The transport of charge carriers through the interface was studied by measuring the current-voltage curves in the dark and under illumination. In the best configuration, we obtain a modest open-circuit voltage of about 70 mV and a short-circuit current of 3.5 mA/cm2 at an illumination of 110 mW/cm2. In order to analyze the effects of the illumination on the electrical properties of the junction, we proposed a model of two opposing diodes, each one associated with an independent current source. We obtain a good accordance between the experimental data and the model. The current-voltage curves in illuminated conditions are well fitted with the same parameters obtained in the dark where only the photocurrent intensities in the diodes are free parameters.

Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

“…10(a) shows a scanningelectron microscopy image of a macro-porous silicon (MPS) substrate, obtained by 425 electrochemical process. The porous silicon methodology was reported in previous works [16,52]. Also, we observe an AZO layer deposited by the spray pyrolysis technique during 20 min, seen as hexagonal structures in the inset of Fig.…”

“…These times led to films with thicknesses of 0.43, 0.67, 0.80, 1.26 and 1.44 µm, respectively. Also, we have deposited these TCO films onto porous silicon substrates (see the synthesis and deposition details in [16]) to produce heterojunction devices. TEA was again used as an additive in the sol-gel process.…”

“…In turn, for the electrical characterization we performed measurements of conductivity as a function of temperature under vacuum and Hall effect at room temperature by the Van der Pauw method. The electrical behavior of the heterojunction was determined by mea-90 suring the characteristic current-voltage (J-V) curves using a Keithley 6487 digital picoammeter (see more details of this setup in [16]). …”

Fabrication and Optoelectronic Properties of Fluoride Tin Oxides/Porous Silicon/p-Silicon Heterojunction

“…5. SnO 2 : F is a direct band gap semiconductor; the band gap is estimated from the plots of (αhv) 2 versus hv and shown in Fig. 5.…”

Fabrication and Optoelectronic Properties of Fluoride Tin Oxides/Porous Silicon/p-Silicon Heterojunction

“…In some cases, these metal contacts are replaced by transparent conductive oxide (TCO), such as tin oxide or zinc oxide, modified with dopants such as fluoride or aluminum, respectively. In these cases, knowledge about the contact properties is very scarce [2][3][4]. Among the various deposition techniques, spray pyrolysis is well suited for the preparation of doped tin oxide thin films because of its simple and inexpensive experimental arrangement, ease of adding various doping materials, reproducibility, high growth rate and mass production capability for uniform large area coatings [5].…”