Bilayer–metal assisted chemical etching of silicon microwire arrays for photovoltaic applications

For decades, fabrication of semiconductor devices has utilized well-established etching techniques to create complex nanostructures in silicon. Of these, two of the most common are reactive ion etching in the gaseous phase and metal-assisted chemical etching (MACE) in the liquid phase. Though these two methods are highly established and characterized, there is a surprising scarcity of reports exploring the ability of metallic films to catalytically enhance the etching of silicon in dry plasmas via a MACE-like mechanism. Here, we discuss a metal-assisted plasma etch (MAPE) performed using patterned gold films to catalyze the etching of silicon in an SF6/O2 mixed plasma, selectively increasing the rate of etching by over 1000%. The degree of enhancement as a function of Au catalyst configuration and relative oxygen feed concentration is characterized, along with the catalytic activities of other common MACE metals including Ag, Pt, and Cu. Finally, methods of controlling the etch process are briefly explored to demonstrate the potential for use as a liquid-free fabrication strategy.

Download Full-text

Influence of Etching Regimes on the Reflectance of Black Silicon Films Formed by Ni-Assisted Chemical Etching

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.806.24 ◽

2019 ◽

Vol 806 ◽

pp. 24-29 ◽

Cited By ~ 1

Author(s):

Olga V. Volovlikova ◽

S.A. Gavrilov ◽

P.I. Lazarenko ◽

A.V. Kukin ◽

A.A. Dudin ◽

...

Keyword(s):

Refractive Index ◽

Treatment Duration ◽

Chemical Etching ◽

Visible Region ◽

High Light ◽

Silicon Films ◽

Black Silicon ◽

Metal Assisted Chemical Etching ◽

Light Absorptance

This paper examines the influence of etching regimes on the reflectance of black silicon formed by Ni-assisted chemical etching. Black silicon exhibits properties of high light absorptance. The measured minimum values of the reflectance (R-min) of black silicon with thickness of 580 nm formed by metal-assisted chemical etching (MACE) for 60 minutes at 460 lx illumination were 2,3% in the UV region (200–400 nm), 0,5% in the visible region (400–750 nm) and 0,3% in the IR region (750–1300 nm). The findings showed that the reflectance of black silicon depends on its thickness, illumination and treatment duration. In addition, the porosity and refractive index were calculated.

Download Full-text

Formation and Evaluation of Silicon Substrate with Highly-Doped Porous Si Layers Formed by Metal-Assisted Chemical Etching

Nanoscale Research Letters ◽

10.1186/s11671-021-03524-z ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

Yijie Li ◽

Nguyen Van Toan ◽

Zhuqing Wang ◽

Khairul Fadzli Bin Samat ◽

Takahito Ono

Keyword(s):

Electrical Conductivity ◽

Seebeck Coefficient ◽

Contact Resistance ◽

Power Factor ◽

Chemical Etching ◽

Porous Si ◽

Si Substrate ◽

Si Substrates ◽

Output Performance ◽

Metal Assisted Chemical Etching

AbstractPorous silicon (Si) is a low thermal conductivity material, which has high potential for thermoelectric devices. However, low output performance of porous Si hinders the development of thermoelectric performance due to low electrical conductivity. The large contact resistance from nonlinear contact between porous Si and metal is one reason for the reduction of electrical conductivity. In this paper, p- and n-type porous Si were formed on Si substrate by metal-assisted chemical etching. To decrease contact resistance, p- and n-type spin on dopants are employed to dope an impurity element into p- and n-type porous Si surface, respectively. Compared to the Si substrate with undoped porous samples, ohmic contact can be obtained, and the electrical conductivity of doped p- and n-type porous Si can be improved to 1160 and 1390 S/m, respectively. Compared with the Si substrate, the special contact resistances for the doped p- and n-type porous Si layer decreases to 1.35 and 1.16 mΩ/cm2, respectively, by increasing the carrier concentration. However, the increase of the carrier concentration induces the decline of the Seebeck coefficient for p- and n-type Si substrates with doped porous Si samples to 491 and 480 μV/K, respectively. Power factor is related to the Seebeck coefficient and electrical conductivity of thermoelectric material, which is one vital factor that evaluates its output performance. Therefore, even though the Seebeck coefficient values of Si substrates with doped porous Si samples decrease, the doped porous Si layer can improve the power factor compared to undoped samples due to the enhancement of electrical conductivity, which facilitates its development for thermoelectric application.

Download Full-text