A method of manufacturing a semiconductor device, the method including, providing a first monocrystalline layer including semiconductor regions, overlaying the first monocrystalline layer with an isolation layer, transferring a second monocrystalline layer comprising semiconductor regions to overlay the isolation layer, wherein the first monocrystalline layer and the second monocrystalline layer are formed from substantially different crystal materials; and subsequently etching the second monocrystalline layer as part of forming at least one transistor in the second monocrystalline layer.