InN-based low dimensional structures
Growth of nitride-based multiple quantum wells (MQWs) or double heterostructures including InN is, however, generally difficult due to large differences in (1) lattice constants and (2) optimal epitaxial growth temperatures between the composite materials of QWs. For the first point, since the lattice mismatch between InN and GaN or AlN is larger than 10%, as shown in Fig. 16.1, a high density of misfit dislocations would be induced at the hetero-interface between InN and GaN or AlN. For the second point, it is known that the optimum growth temperature of InN is about 500-600◦C, which is much lower than that of GaN (about 800◦C) in molecular beam epitaxy (MBE) [16.1]. Therefore, InN-based quantum well structures should be generally grown at temperatures lower than 600◦C, which causes big difficulties for getting high crystalline quality heteroepitaxial layers of GaN, AlN and their ternary alloys.