Heteroepitaxy of GaN on Si(111)

The growth of high-quality group-III-nitrides on silicon is very attractive for low-cost optoelectronic and electronic devices such as light emitting diodes or field effect transistor. However, attempts to grow GaN on Si suffered from large lattice and thermal mismatch and the strong chemical reactivity of Ga and Si at elevated temperatures so far. The latter problem can be easily solved using gallium-free seed layers AlN. The key problem for device structure growth on Si is the thermal mismatch leading to cracks for layer thicknesses above 1 μm. The cracks can be overcome by several concepts as, e.g patterning the substrate and/or the insertion of low-temperature (LT) AlN interlayers which enable the growth of device-relevant GaN thicknesses.