An integration concept which involves the selective deposition of quantum wells in spatially selected areas of a wafer and in the middle of a waveguide structure is presented for the first time. The selective deposition is achieved by the in situ insertion and removal of a shadow mask during the growth process. The shadow-mask concept, and data on alignment and edge definition are presented. Experimental results on selectively grown quantum wells show that the shadow mask has no effect on the non-radiative carrier lifetime even when only a single quantum well is selectively deposited. The performance of laser diodes fabricated using this novel integration technique is compared with broad area devices grown without a shadow mask. Crown Copyright