Patent ID: 7566898

Claim:
An apparatus comprising: a silicon (Si) substrate; a dislocation filtering buffer formed over the Si substrate, the dislocation filtering buffer including: a first buffer layer including a gallium arsenide (GaAs) nucleation layer and a GaAs buffer layer; and a second buffer layer formed on the first buffer layer, the second buffer layer comprising a graded indium aluminium arsenide (InAlAs) buffer layer; a lower barrier layer formed on the second buffer layer, the lower barrier layer formed of InAlAs or indium gallium aluminium arsenide (InGaAlAs), wherein the second buffer layer is formed of aluminium arsenide (AlAs) at an interface with the first buffer layer and is graded with increasing concentration of indium (In) to obtain an In concentration of at least approximately 60%, and is then inverse graded with decreasing concentration of In to attain an In concentration of approximately 52% at an interface with the lower barrier layer; a quantum well (QW) layer formed on the lower barrier layer, wherein the quantum well layer comprises a strained layer formed of indium gallium arsenide (InGaAs); a spacer layer formed over the quantum well layer; a delta-doped layer formed over the spacer layer; and an upper barrier layer formed over the delta-doped layer, the upper barrier layer formed of InAlAs and having an In concentration substantially equal to the In concentration of the lower barrier layer.