Tetsuya Hattori

Inductively Coupled Plasma-Enhanced Chemical Vapor Deposition of SiO2 and GeO2?SiO2 Films for Optical Waveguides Using Tetraethylorthosilicate and Tetramethylgermanium

SiO2 and GeO2–SiO2 films have been deposited by employing inductively coupled plasma-enhanced chemical vapor deposition (ICP-CVD) from tetraethylorthosilicate (TEOS) and oxygen discharge using tetramethylgermanium (TMGe) as a dopant. A pure SiO2 film deposited with TEOS:O2 at a flow rate ratio of 17% and an operating pressure of 5 Pa showed a low wet-etching rate of 114 nm/min approaching that of a thermally grown oxide. Ge doped SiO2 films were deposited at various TMGe flow rates, and it was found that Ge was incorporated into the film as a replacement for Si. The refractive index of the film is in proportion to the Ge content in the film. Fourier transform infrared (FTIR) analysis confirmed that there were few O–H and C–H defects in the films. Optical waveguides were fabricated using ICP-CVD and reactive ion etching (RIE). A propagation loss of 0.027 dB/cm at 1.55 µm was achieved for the optical waveguide by using GeO2–SiO2 film as the core layer.

Optical properties of ZnSe diffractive optical elements for spot array generation

The diffractive optical element (DOE) is a revolutionary technology for sophisticated optical systems. It has recently been launched within the optical industry, which is constantly seeking improvements over conventional optics. We have designed and fabricated three types of binary-phase DOE for array generation. The surface relief of a ZnSe substrate was patterned and etched with each intended phase distribution by using photolithography and reactive ion etching (RIE) technologies. The optical properties of anti-reflection coated samples were then examined by measuring the intensity distribution of their converging diffractive beams and the results compared with the calculated beam propagation.

A 25-nm-pitch GaInAs/InP Buried Structure Using Calixarene Resist.

To realize a fine periodical pattern by electron beam lithography, a stady for using calixarene as a resist was carried out. A 25-nm-pitch resist pattern was fabricated and transferred to a thin InP layer by two-step wet chemical etching. Precise slight O2 ashing, to eliminate residual matter was essential to transfer the pattern by wet etching. The controllability of the width was improved when using calixarene, when the period was 40 nm. Furthermore, a 25-nm-pitch InP pattern was buried in a GaInAs structure by organometallic vapor phase epitaxy. This technology could be applied to realize electron wave devices.