Selective etching of n-InP(1 0 0) triggered at surface dislocations induced by nanoscratching

This work investigates selective dissolution of n-InP(1 0 0) triggered by surface defects. Nanometer size grooves were produced by sensitizing an InP surface with a mechanical contact patterning technique, i.e. nanoscratching at low loading forces at the threshold between elastic and plastic contacts. Subsequently, site-selective electrochemical dissolution was triggered in a 1 M HCl electrolyte. Electrochemical characterization shows that there is an onset voltage for selective dissolution at the scratch-induced defects and that it is possible to define a processing potential window where dissolution occurs only inside the nanoscratches. Scanning electron microscopy (SEM) micrographs reveal that for optimized forces, highly confined dissolution in well-defined channels of 125 nm width can be obtained. Transmission electron microscopy (TEM) cross sectional analysis of the scratches before and after electrochemical experiments shows that the dislocations generated are confined in a well-defined volume below the surface, and that exactly this dislocated volume is dissoluted. Indeed, the site-selective activation must be ascribed to these surface dislocations. Based on contact mechanics, the lateral resolution and the morphology of the dissolved groove can be explained by the dissolution time and the tip radius and the morphology by the applied load.