| 摘要 |
A method of growing an AlGaN semiconductor layer structure by Molecular Beam Epitaxy comprises supplying ammonia, gallium and aluminium to a growth chamber thereby to grow a first (Al,Ga)N layer (4) by MBE over a substrate (2) disposed in the growth chamber. The first (Al,Ga)N layer (4) has a non-zero aluminium mole fraction. Ammonia is supplied at a beam equivalent pressure of at least 1x10<-4> mbar, gallium is supplied at a beam equivalent pressure of at least 1x10<-8> mbar and aluminium is supplied at a beam equivalent pressure of at least 1x10<-8> mbar during the growth step. Once the first (Al,Ga)N layer (4) has been grown, varying the supply rate of gallium and/or aluminium enables a second (Al,Ga)N layer (5), having a different aluminium mole fraction from the first (Al,Ga)N layer to be grown by MBE over the first (Al,Ga)N layer. This process may be repeated to grown an (Al,Ga)N multilayer structure (3). |
