Samuel Menard

Non-oxidized porous silicon-based power AC switch peripheries

We present in this paper a novel application of porous silicon (PS) for low-power alternating current (AC) switches such as triode alternating current devices (TRIACs) frequently used to control small appliances (fridge, vacuum cleaner, washing machine, coffee makers, etc.). More precisely, it seems possible to benefit from the PS electrical insulation properties to ensure the OFF state of the device. Based on the technological aspects of the most commonly used AC switch peripheries physically responsible of the TRIAC blocking performances (leakage current and breakdown voltage), we suggest to isolate upper and lower junctions through the addition of a PS layer anodically etched from existing AC switch diffusion profiles. Then, we comment the voltage capability of practical samples emanating from the proposed architecture. Thanks to the characterization results of simple Al-PS-Si(P) structures, the experimental observations are interpreted, thus opening new outlooks in the field of AC switch peripheries.

P type porous silicon resistivity and carrier transport

The resistivity of p type porous silicon (PS) is reported on a wide range of PS physical properties. Al/PS/Si/Al structures were used and a rigorous experimental protocol was followed. The PS porosity (P%) was found to be the major contributor to the PS resistivity (ρPS). ρPS increases exponentially with P%. Values of ρPS as high as 1 × 109 Ω cm at room temperature were obtained once P% exceeds 60%. ρPS was found to be thermally activated, in particular, when the temperature increases from 30 to 200 °C, a decrease of three decades is observed on ρPS. Based on these results, it was also possible to deduce the carrier transport mechanisms in PS. For P% lower than 45%, the conduction occurs through band tails and deep levels in the tissue surrounding the crystallites. When P% overpasses 45%, electrons at energy levels close to the Fermi level allow a hopping conduction from crystallite to crystallite to appear. This study confirms the potential of PS as an insulating material for applications such as power e...

Investigation of direct current electrical properties of electrochemically etched mesoporous silicon carbide

In this study, we show I-V characterizations of various metal/porous silicon carbide (pSiC)/silicon carbide (SiC) structures. SiC wafers were electrochemically etched from the Si and C faces in the dark or under UV lighting leading to different pSiC morphologies. In the case of low porosity pSiC etched in the dark, the I-V characteristics were found to be almost linear and the extracted resistivities of pSiC were around 1.5 × 104 Ω cm at 30 °C for the Si face. This is around 6 orders of magnitude higher than the resistivity of doped SiC wafers. In the range of 20-200 °C, the activation energy was around 50 meV. pSiC obtained from the C face was less porous and the measured average resistivity was 10 Ω cm. In the case high porosity pSiC etched under UV illumination, the resistivity was found to be much higher, around 1014 Ω cm at room temperature. In this case, the extracted activation energy was estimated to be 290 meV.

Porous silicon formation by hole injection from a back side p+/n junction for electrical insulation applications

In this paper, we propose to study the formation of porous silicon (PS) in low doped (1 × 1014 cm−3) n-type silicon through hole injection from a back side p+/n junction in the dark. This technique is investigated within the framework of electrical insulation. Three different types of junctions are investigated. The first one is an epitaxial n-type layer grown on p+ doped silicon wafer. The two other junctions are carried out by boron diffusion leading to p+ regions with junction depths of 20 and 115 μm. The resulting PS morphology is a double layer with a nucleation layer (NL) and macropores fully filled with mesoporous material. This result is unusual for low doped n-type silicon. Morphology variations are described depending on the junction formation process, the electrolyte composition, the anodization current density and duration. In order to validate the more interesting industrial potentialities of the p+/n injection technique, a comparison is achieved with back side illumination in terms of resulting morphology and experiments confirm comparable results. Electrical characterizations of the double layer, including NL and fully filled macropores, are then performed. To our knowledge, this is the first electrical investigation in low doped n type silicon with this morphology. Compared to the bulk silicon, the measured electrical resistivities are 6–7 orders of magnitude higher at 373 K.

A vertical bidirectional bipolar power switch (BipAC) for AC mains applications

A vertical bipolar bidirectional switch (BipAC) is proposed for specific AC mains applications 230 V - 50 Hz. The BipAC exhibits an ON-state voltage drop lower than 1 V and allows an ON-state and OFF-state control with respect to a single electrode which is at the reference potential. It can be realized either on an N substrate (type PNP) or on a P substrate (type NPN). Its low voltage drop and its ON/OFF control with respect to a single reference electrode make it interesting for applications with low load current (<; 1 A rms). This study is based on 2D physical simulations carried-out using Sentaurus™ software.

Fabrication of nanostructured porous silicon for power switch peripheries

The tunable semi-insulating nature of nanostructured porous silicon gives rise to a potential application in semiconductor industry - power switch periphery. In this work, fabrication of nanostructured porous silicon by anodic etching is investigated. The relationship between anodization conditions and resulting morphology is defined. Our work demonstrates that, by careful tuning structure, thickness and porosity, well-engineered nanostructured porous silicon enables controlling electronic insulation properties, which certainly broaden the design option of power device periphery.