InP Etch Pit Morphologies Revealed by Novel HCI Based Etchants.

A new dislocation etchant for InP has been developed which consists of HBr:H sub 2 O sub 2 :HCI:H sub 2 O in volume ratio of 20:2:20:20. This etchant reveals distinct etch pits with a threefold symmetry on the (111)P surface. On the (001) wafer surfaces, the etched pits have a pyramidal shape and they are elongated along one of the directions with four {111} side walls planes. The longer dimension of the rectangular pits on (001) wafers etched by this solution is perpendicular to that etched by HBr-based solution. The characteristics of this new etchant can be charged from a dislocation etchant to a polishing solution by increasing the H sub 2 O sub 2 volume ratio. This new etchant can have a substantially longer shelf time (~12 hours) than the conventional HBr-based etchant. The use of the conventional etchants imposes a severe limitation on processing the desirable laser structure. By mixing a proper ratio of our new etchant with the conventional HBr- based etchants we can have a new degree of freedom in laser fabrication.