High aspect ratio deep etching in GaInAsSb/AlGaAsSb system by ICP-RIE plasma

GaSb based compound semiconductors emit in the mid-infrared range and present extremely good optoelectronic properties, with demonstrated bipolar laser diodes emitting from 2 to 3.5 µm with good performances. Such diodes are often made with a core waveguide embedded in claddings made of AlGaAsSb with high Al content. Deep etching of high Al content claddings is known to be a particular challenge for deep etching with high aspect ratio, and restricts the designs achievable for laser diodes fabrication. In this paper, we present our work on deep etching of sub-micron air holes in GaInAsSb/AlGaAsSb heterostructures with 65% Al content. High aspect ratio of 7 is achieved for 350 nm diameter holes.