Infrared semiconductor ring laser fabrication typically involves planarization of ridge waveguide device structures and deposition of metal electrodes for electrical pumping. Uniform planarization across large samples is difficult to achieve. This leads to inadequate electrical contact between portions of the ring resonator and the deposited metal electrode layer whereby the devices are not optimally pumped. This can lead to high threshold currents and device failure. The problem of inadequate electrical pumping on account of non-idea planarization has been addressed by utilizing a metallic etch mask instead of the commonly used photoresist 'soft' mask. The metallic mask remains intact after ridge etching and the other ensuing fabrication steps to form a continuous metallic cover above the entire device structure. This metallic cover ensures proper electrical contact between the ring resonator and the deposited metal electrode layer even when planarization imperfections render only certain portions of the resonator in proper electrical contact with the metal electrode layer. The proposed fabrication process has led to large diameter ring lasers with high yield and low threshold current levels. These devices are robust and exhibit stable operation over large current ranges in addition.

Date Published: 23 February 2009
PDF: 8 pages
Proc. SPIE 7204, Micromachining and Microfabrication Process Technology XIV, 720404 (23 February 2009); doi: 10.1117/12.809715

Published in SPIE Proceedings Vol. 7204:
Micromachining and Microfabrication Process Technology XIV
Mary-Ann Maher; Jung-Chih Chiao; Paul J. Resnick, Editor(s)