A superlattice semiconductor device comprises superlattice layers (4a, 4a', 5a) stacked on the whole surface of a trench (20) formed in a semiconductor substrate or on the whole surface of a projection (30) extending from a surface of the semiconductor substrate....http://www.google.de/patents/US5621222?utm_source=gb-gplus-sharePatent US5621222 - Superlattice semiconductor device
