Low defect, high purity crystalline layers grown by selective deposition

Claim 1

A semiconductor article comprising: a blank of semiconductor having a first level of impurities; a film of a first mask having a pattern of openings applied to a surface of the blank and said film being impervious to diffusion of said impurities from said semiconductor surface; a first continuous layer of grown semiconductor on said mask extending from said openings over the bridges of mask between the openings to form a first continuous layer of semiconductor having a lesser level of impurities and defects than said blank, and having less defects and impurities in areas overlying said bridges than areas overlying said openings; a second film of mask impervious to diffusion of said impurities having a pattern of openings in registration with the bridges of the first mask and a pattern of bridges overlying the openings in the first mask; and a second continuous layer of semiconductor grown on said second mask having a lower impurity and defect level than the first layer, said second layer extending from said openings and over the bridges of the second mask to form said second continuous layer.