Double-etching technique for the fabrication of submicron channels on a GaAs wafer and its application to laser fabrication

We demonstrate in this paper a simple, reproducible, uniform, and reliable double-etching technique which enables us to make submicron channels on a GaAs wafer from a photomask of considerably larger dimension. Only conventional photolithographic process and preferential etching are required. The technique consists of stripping the photoresist after a first-step preferential etching and then immersing the wafer back into the etchant to perform the second etching. As a first example, we have applied this technique to the fabrication of a channeled-substrate planar laser using liquid-phase epitaxy. The surface morphology of the LPE layers and the performance of the laser are shown to be of superior quality.