Over 1.5 µm Deep Dry Etching of Al-Rich AlGaAs for Photonic Crystal Fabrication

Abstract

We investigate inductively coupled plasma deep dry etching of Al0.8Ga0.2As for photonic crystal (PC) fabrication using the Cl2, BCl3, and CH4 mixture. On the basis of our previous work [M. Mochizuki et al.: Jpn. J. Appl. Phys. 50 (2011) 04DG15], we explore the deeper dry etching of the PC structure, investigating the impact of gas flow rate and chemical reactions. Increasing gas flow rate and process pressure resulted in deeper etching. These conditions increased the self-bias applied on the sample, which induced the sharpening of the air hole bottom and limitation of further deep etching because of the strong contribution of physical etching. The reduction of CH4 gas suppressed the sidewall passivation, counteracting the effect of the physical etching. As a result, we obtained a PC structure having air holes with a depth larger than 1.5 µm and a diameter of 120 nm.

Dry etching of Al-rich AlGaAs with silicon nitride masks for photonic crystal fabrication

“…However, too great of a physical etching effect during the entire etching process may sharpen the bottom of the air holes and limit further deep etching. 14) On the other hand, antenna power plays an important role in dissociating mixed gas molecules into reactive radicals and ionic species, and thus in increasing the plasma density and chemical etching effect. The chemical etching effect causes the etching process to be isotropic and the vertical profile of the air holes to be round.…”

“…13) Recently, we have reported a PC structure with air holes deeper than 1.5 µm and a diameter of 120 nm fabricated using SiO 2 as the mask layer. 14) In this case, the gas flow rate and process pressure were carefully adjusted to achieve greater etching depth. However, the air hole arrays we achieved had a diameter smaller than the nominal 200 nm and a shape approximately like a reverse cone, mainly because of mask retardation, as shown in Fig.…”

Improved luminescence from tensile-strained compound semiconductor quantum wells with dielectric-rod photonic crystals

“…21) The PC on the surface was fabricated by inductively coupled plasma etching using a Cl 2 /BCl 3 /CH 4 gas mixture. 22) The PC rods were patterned using electron beam lithography through a Cr mask. The rod height was about 250 nm, which affects the behavior of light confined between the bottom-side AlGaAs and the top-side air having a thickness of 300 nm, which is about 1/n for the emission wavelength of 890 nm of the GaInNAs gain medium.…”

Oblique Deposition of Ti/Pt/Au Electrode on Photonic Crystal for Vertical Current Injection

“…According to the rate equation calculations [4,7,17], a single CirD laser can be directly modulated at a rate of 50 Gbps under the injection current of 400 µA, and thus a 20-channel CirD laser array can be expected to reach an extremely high bandwidth density of 10 Pbps/cm 2 [4]. In our previous studies, the verticality of the profile of the 1.5-μm-deep air holes was improved to ensure the quality of the PhC structure [18,19]. Selective oxidation of AlGaAs was studied to obtain the ideal oxidization parameters for good light confinement [20].…”

“…Using this, the electrical characteristics are estimated to confirm that there is no leakage of current and the resistance of the structure is sufficiently low. In our previous studies, the verticality of the profile of the 1.5-µm-deep air holes was improved to ensure the quality of the PhC structure [18,19]. Selective oxidation of AlGaAs was studied to obtain the ideal oxidization parameters for good light confinement [20].…”