Effect of H2 on the etch profile of InP/InGaAsP alloys in Cl2/Ar/H2 inductively coupled plasma reactive ion etching chemistries for photonic device fabrication

This study demonstrates etch profile engineering of InP, ${\mathrm{In}}_{\text{1−x}}{\mathrm{Ga}}_x{\mathrm{As}}_{\text{1−y}}{\mathrm{P}}_y,$ and ${\mathrm{In}}_{\text{0.53}}{\mathrm{Ga}}_{\text{0.47}}\mathrm{As}$ heterostructures results from adding ${\mathrm{H}}_2$ to standard ${\mathrm{Cl}}_2/\mathrm{Ar}$ inductively coupled plasma-reactive ion etching chemistries. Etch rate curves of bulk InP, ${\mathrm{In}}_{\text{1−x}}{\mathrm{Ga}}_x{\mathrm{As}}_{\text{1−y}}{\mathrm{P}}_y,$ and ${\mathrm{In}}_{\text{0.53}}{\mathrm{Ga}}_{\text{0.47}}\mathrm{As}$ show a general parabolic trend as a function of the ${\mathrm{H}}_2$ component of the ${\mathrm{Cl}}_2/\mathrm{Ar}/{\mathrm{H}}_2$ ratio. Three distinct etching profiles of InP/InGaAsP layers were realized by varying the ${\mathrm{Cl}}_2/\mathrm{Ar}/{\mathrm{H}}_2$ ratio. Highly anisotropic profiles result for ${\mathrm{Cl}}_2/\mathrm{Ar}/{\mathrm{H}}_2$ ratios between 2/3/1 and 2/3/2. Waveguiding structures fabricated using this technology are presented with a loss as low as 2 dB/cm. An InP racetrack resonator with a quality factor $\text{(Q)>8000}$ is also presented.