InGaN Laser Diode with Spin-on-Glass Isolation Fabricated by Planarization and Etch-Back Process

TL;DR

This paper introduces a new method for making InGaN laser diodes using spin-on-glass for insulation, which is cheaper and simpler than traditional methods.

Contribution

The novel use of spin-on-glass (SOG) for insulation in InGaN laser diodes reduces cost and complexity compared to conventional PECVD-deposited SiO2.

Findings

SOG-based insulation provides better surface planarity and adhesion to ridge sidewalls.

Devices with Ni protective layers showed good electrical and optical performance.

Laser operation was stable under both pulsed and continuous-wave conditions.

Abstract

We report on the fabrication and characterization of InGaN-based ridge-waveguide laser diodes employing spin-on-glass (SOG) as the insulation and planarization layer. In contrast to conventional silicon dioxide (SiO2) isolation deposited by PECVD, the SOG approach provides improved surface planarity, reduced processing complexity, and lower fabrication cost. The laser structures were grown on GaN substrates by MOCVD, with the active region consisting of In0.11Ga0.89N quantum wells. Following ridge formation and SOG deposition, an etch-back process was used to form the electrical contacts. We have demonstrated the formation of high-quality insulating surfaces with strong adhesion to the ridge sidewalls. When using a Ni protective layer, the fabricated devices exhibited favorable electrical and optical characteristics and achieved stable laser operation under both pulsed and continuous-wave conditions. These results indicate that the SOG-based insulation process represents a promising alternative for the scalable and cost-effective fabrication of InGaN laser diodes targeting advanced photonic applications.

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