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

Abstract

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.

Electrochemical etching modes of 4H-SiC in KOH solutions

“…Several studies have applied electrochemical methods in electrochemical mechanical polishing [17][18][19][20], nanoporous SiC preparation [21][22][23][24][25][26][27][28], defect characterization [29], and micromachining of microelectronics [30,31]. However, these investigations on concentrated micromachining suffer from issues of low etching rates and poor surface morphology.…”

A Combination of Metal Assisted Photochemical and Photoelectrochemical Etching for Tailored Porosification of 4H SiC Substrates

“…Underneath the originally deposited Pt pads (see Figure 1), porous SiC had been formed during the first MAPCE and PECE step. Since the electrical conductivity of porous SiC is lower than the corresponding bulk value, 23 the necessary electron transport for MAPCE is diminished. 19 Therefore, a 300 nm thin Pt layer was deposited at regions of the sample where no porous layer had been formed and annealed.…”

Optical properties of mesoporous 4H-SiC prepared by anodic electrochemical etching

“…When transformed from bulk into a porous material, visible room temperature PL is observed for porous Si (por-Si), [3][4][5] which in turn initiated interest in porous SiC (por-SiC). [6][7][8][9][10][11][12] The enhanced blue-green PL in por-SiC has been studied for applications in light emitting devices. [13][14][15] The strong absorption in the ultraviolet (UV) has applications for photodetectors, 16,17 while the large surface area is suitable for gas sensors.…”