Improved surface quality of anisotropically etched silicon {111} planes for mm-scale integrated optics

TL;DR

This study compares the surface quality of silicon mirrors etched in KOH from CZ and FZ wafers, finding FZ wafers produce significantly lower noise and higher optical quality for mm-scale integrated optics.

Contribution

It demonstrates that FZ silicon wafers yield superior surface quality and lower noise in etched {111} silicon mirrors compared to CZ wafers.

Findings

FZ wafers have four times lower noise power at certain spatial frequencies.

Mirrors from FZ wafers exhibit higher optical quality.

FZ wafer etching results in better surface smoothness.

Abstract

We have studied the surface quality of millimeter-scale optical mirrors produced by etching CZ and FZ silicon wafers in potassium hydroxide to expose the $\{111\}$ planes. We find that the FZ surfaces have four times lower noise power at spatial frequencies up to $500\, {mm}^{-1}$. We conclude that mirrors made using FZ wafers have higher optical quality.