Magnesium Aluminate(MgAl2O4 or spinel) singel crystal widely used for bulk acoustic wave and microwave devices and fast IC epitaxial substrates. MgAl2O4 is an attractive material for uses in a wide require excellent transmission from the visible through to the mid IR. Theoretical transmission is very uniform and approaches 87% between 0.3 to 5 microns. Transmission characteristics rival that of ALON and sapphire in the mid-wave IR, making it especially attractive for the ever-increasing perfor-mance requirements of current and next-generation IR imaging systems.
It is also found that MgAl2O4 is a good substrate for Ⅲ-Ⅴnitrides devices. Spinel(MgAl2O4) is one candi-date for such GaN LDs substrate. The crystallo-graphic structure of MgAl2O4 is a spinel type(Fd3m),and its lattice constant is 8.083 A. MgAl2O4 is a relatively low-cost substrate materi-al,which has been successfully applied to the growth of high quality GaN films.MgAl2O4 is cleaved on the(100)plane. GaN LD cavities have been obtained by simply cleaving MgAl2O4 substrates along the
(100) direction, which wiil also work well for ZnO.MgAl2O4 crystal is very difficult to grow, due to difficulty in maintaining a single phase structure.